Meibion Glyndŵr (, also known by its translation Sons of Glyndŵr) was a Welsh nationalist paramilitary group which carried out 328 attacks, including 228 arson attacks against holiday cottages in Wales owned by English people, and other attacks against government offices and estate agent offices between 1979 and 1993.

The organisation was founded in 1979, during a period of increasing nationalist sentiment in Wales. During this period, significant sections of Welsh public opinion opposed the purchase of second homes or holiday cottages in Wales by English buyers, regarding it as a contributing factor to rising housing prices and a potential threat to Welsh-speaking communities. The first attacks occurred in the early hours of 13 December 1979, during which a holiday home in Nefyn, another in Llanbedrog, two in Pennal near Machynlleth, and a further two in Pembrokeshire were set alight. This marked the beginning of the arson campaign. In the first wave of attacks, twenty-two English-owned holiday homes were destroyed within the space of a month. The campaign reached its peak in the late 1980s with the targeting of Conservative Party MP<nowiki/>s' homes with letter bombs, most notably that of David Hunt, the then Secretary of State for Wales, who was targeted in 1990.

Four separate movements claimed responsibility for the bombings: Mudiad Amddiffyn Cymru ("Movement for the Defence of Wales"), Cadwyr Cymru ("Keepers of Wales"), Meibion Glyndŵr, and the Workers' Army of the Welsh Republic (WAWR), whose attacks were on political targets in the early 1980s. Following the wave of initial attacks, John Barnard Jenkins, former leader of Mudiad Amddiffyn Cymru (MAC) and a key figure in its bombing campaign in the 1960s, was interviewed on the BBC programme Nationwide on 12 March 1980. Jenkins had initially been interviewed by BBC Wales' Heddiw the day after the first attacks on 13 December 1979; however, the interview was never broadcast. During the Nationwide broadcast, Jenkins outlined the motivations for those involved in the arson campaign and suggested that those responsible were associated with MAC, noting that most of the organisation's cells were never identified following the 1960s bombing campaign. Meibion Glyndŵr was the only group to have any claim to long-term success, although since the mid-1990s the group has been inactive, and Welsh nationalist violence has ceased, at least on an organisational level.

Operation Tân

On 30 March 1980, Special Branch and Welsh police conducted a large series of dawn raids as part of Operation Tân ("Fire") in an effort to identify those responsible for the arson attacks. The coordinated raids are often referred to in relation to their timing in the early hours of Palm Sunday, also known in Welsh as Sul y Blodau ("Flowering Sunday"). Approximately fifty individuals were arrested during the operation, most of whom were in some way associated with Welsh nationalism. Among them was former Free Wales Army (FWA) organiser Gethin ap Gruffydd and his wife Sian Ifan, who were released two days later due to a lack of evidence linking them to the arson campaign.

In January 1982, controversy arose in Wales following claims that a couple living near the village of Talysarn in Gwynedd had witnessed two plain-clothed police officers installing bugging devices in a telephone kiosk. When confronted, the alleged officers reportedly claimed to be working for the General Post Office; however, investigations by local police revealed that the Birmingham-registered vehicle used by the men was an undercover police car. Later commenting on the affair, local MP Dafydd Wigley stated: "The secret agents were not associated with the local constabulary; they were acting without authority; and there was no process of public answerability." The incident was satirised by folk singer Dafydd Iwan and the band Ar Log in the song titled "Ciosg Talysarn" ("Talysarn Kiosk"), which mocked the extent of police surveillance efforts in Wales during the Meibion Glyndŵr campaign.

Parti Lliw Meibion Glyndŵr

left|thumb|Parti Lliw Meibion Glyndŵr at the grave of George Taylor in [[Abergele. John Barnard Jenkins is seen holding a wreath on the right, 1989.|274x274px]]

In July 1989, eight men wearing paramilitary uniforms marched in a procession attended by 250 people in Abergele to commemorate the deaths of two alleged members of Mudiad Amddiffyn Cymru. The two, named Alwyn Jones and George Taylor, who are often referred to by Welsh nationalists as the "Abergele Martyrs", were killed when the bomb they were planting prematurely exploded on the eve of King Charles III's investiture as the Prince of Wales in July 1969. On the chest of the group's uniforms was a badge bearing the words (), featuring a heraldic white eagle, a symbol commonly associated with radical Welsh nationalism since its popularisation by the FWA in earlier decades. and David Gareth Davies were among those within the colour party, both of whom were later arrested on suspicion of involvement with Meibion Glyndŵr and subsequently cleared. Also present was , who was the sole individual that was later convicted for involvement in the organisation. Charges focused on allegations that Roberts had sent four incendiary devices in the post to two senior police officers and two senior members of the Conservative Party, including Baron Roberts of Conwy. During the eight-week trial in Caernarfon, it was revealed that MI5 officers had repeatedly broken into Roberts' flat to conduct searches and plant bugging devices in the property. Nigel Mylne, for the defence, suggested that MI5 had planted incriminating evidence in Roberts' flat, citing what he described as the authorities' frustration at failing to secure an arrest during twelve years of the arson campaign. Dewi Prysor has described Iwan's stance as "fantasy", stating: "I greatly admire Dafydd, but I think he felt, as a pacifist, that the actions of Meibion Glyndŵr would damage Plaid Cymru and Welsh nationalism, so he came up with this notion that the arson campaign was planned and executed by the British state."

Roberts was ultimately found guilty and sentenced to 12 years in prison, The final attack associated with Meibion Glyndŵr occurred a week after Roberts' trial, in which a Molotov cocktail was used to firebomb a holiday home named "Rose Cottage" in Gwalchmai, close to Roberts' home in Anglesey. The letters MG (for "Meibion Glyndŵr") were painted on the gable of the house. Roberts was also interviewed by the BBC in 2023 for its Firebombers documentary, during which he reiterated his admission of involvement with Meibion Glyndŵr, citing the policies of Margaret Thatcher’s government as his motivation for turning to militant action.

At the height of the Meibion Glyndŵr arson campaign, a poll was conducted by HTV’s Welsh-language current affairs programme on S4C, Y Byd ar Bedwar (). 1,195 people across Wales were questioned about their attitudes towards the campaign and, despite 69% claiming they would assist police if a local holiday home was burnt down, 57% said they supported the broader aims of the campaign. However, support for the campaign was far greater in Welsh language strongholds, where the second home issue was most obvious, and consequently 85% of respondents from Dwyfor supported the campaign. Meibion Glyndŵr merchandise become so widespread that the director of the 1989 Dyffryn Conwy National Eisteddfod in Llanrwst warned that anyone caught selling merchandise that supported the arson campaign would be immediately banned from the event. Thomas' comments drew criticism from then Plaid Cymru president Dafydd Wigley, who reportedly warned: "If we don't get it sorted out we're going down the road to Northern Ireland", referring to The Troubles. Thomas later commented in 1998, in the context of his support for the militant organisation, "What is one death against the death of the Welsh nation?" Supporters of Wrexham A.F.C. sang chants at opposing English teams glorifying the actions of the arsonists.

thumb|269x269px|[[Bryn Fôn was arrested by police in connection with the arson campaign shortly after his "Meibion y Fflam" performance]]

Following a public appeal for witnesses on Crimewatch, Welsh actor and singer-songwriter, Bryn Fôn, wrote a song titled "" (), intended to belittle the police’s failed attempts at catching the arsonists. The song was released in 1989 by the band Sobin a’r Smaeliaid, of which Bryn Fôn was the lead singer. In 1990, detectives visited Fôn’s home in Llanllyfni and arrested both Bryn and his partner, Anna, after discovering a package hidden in a stone wall on his cottage’s land, which police alleged contained the components required to construct a bomb. After holding both Fôn and his partner at Dolgellau police station for 48 hours, police released both of them without charge. His C'mon Midffîld! co-star, Mei Jones, and another Welsh actor, Dyfed Thomas, were also arrested at the same time, with both being later released without charge.

Speaking on S4C's investigative ' () in 2004, the former head of North Wales Police CID, Detective Chief Superintendent Gareth Jones, alleged that many within the force were sympathetic to the arsonists. Jones had been responsible for heading the police unit tasked with the investigation into Meibion Glyndŵr at the time of the firebombing campaign. Commenting on the matter, Jones stated, "There's no doubt that some police outside this unit were supportive of what was going on. I have no doubt about that, and we had to co-operate and work with those people - but nobody was open about it at the time, of course."

Armed campaign

  • 1979–91: Meibion Glyndŵr conducted arson attacks on 239 English-owned holiday homes. On the same day, a Conservative Party branch in Cardiff is firebombed by the group.
  • 26 October 1981: An improvised device in an army recruiting office is defused in Pontypridd, prior to a visit by the Prince of Wales. Two days later another bomb is defused by authorities.
  • 28 June 1987: Welsh extremists leave two improvised devices in Abergele and Porthmadog.
  • 1988–89: Meibion Glyndŵr declare that "every white settler is a target". The group also places incendiary bombs in Conservative Party offices in London and estate agents' offices in London, Liverpool, Sutton Coldfield, Haverfordwest, Carmarthen and Llandeilo.
  • 18 March 1989: A series of arson attacks takes place in Sutton Coldfield, Haverfordwest, Liverpool and London.
  • 22 October 1989: A new ring of arson attacks begin, this time focusing on London.
  • 20–21 June 1990: Four letter bombs are received. Two are addressed to the Secretary of State for Wales and the Member of Parliament for Pembroke at the House of Commons, and one of the letters slightly wounds a woman. One is addressed to the Secretary of State for Wales David Hunt, and the last to Nicholas Bennett, both of which are defused.
  • 16 September 1990: R. S. Thomas calls for a campaign to deface English-owned homes.
  • 26 March 1993: Sion Aubrey Roberts, a member of Meibion Glyndŵr, is jailed for twelve years for sending letter bombs to Conservative politicians.