Hywel Heulyn Roberts traced his commitment to the cause of Plaid Cymru to the night of 8 September 1936 when some huts and contractors' materials belonging to an RAF bombing school, then being built at Penyberth on the Llyn Peninsula, were set on fire by three of the party's leaders. He was staying at the time with his grandmother in Pwllheli and was among the first to inspect the damage caused by this symbolic act of arson. The excitement caused by "The Fire in Llyn", as the incident came to be known, affected him deeply, for this was the first time in centuries a blow had been struck against a London government riding roughshod over local sensibilities.
When the three perpetrators - Saunders Lewis, D J Williams and Lewis Valentine - stood trial at Caernarfon Assizes, the jury failed to reach a verdict, but at the Old Bailey the following January they were each sentenced to nine months' imprisonment.
Roberts felt the sense of outrage more than most, drawing from the incident much of his pacifism and his conviction that Wales should no longer be governed from London. When, in 2007, he published his autobiography, he called it Tân yn fy Nghalon ("Fire in my Heart").
A sense of Welsh patriotism had been nurtured in him as a boy growing up in Aigburth, a suburb of Liverpool, where he had been born in 1919. The city in those days had a thriving Welsh-language culture based on the chapel, Sunday school and eisteddfod, and on close family links with North Wales, for which it served faute de mieux as a capital. Educated at the Liverpool Institute High School for Boys, he proudly wore a leek in his lapel on St David's Day and sang, to the tune of "Jerusalem", "In Wales's green and pleasant land", while his parents saw to it that he spent every holiday with his grandparents in Pwllheli.
When the time came for him to leave the Institute, his father having lost his job as an engineer with the White Star shipping company, he began work with Martins Bank in its Brunswick Street branch, Liverpool, in September 1936, barely a fortnight after the Fire in Llyn.
He remained at the bank throughout the Second World War, having registered as a conscientious objector on Christian pacifist grounds: "I base my objection to military service," he told the tribunal, "on the Christian religion which I profess and in whose teaching I have been brought up from my earliest days." He had first-hand experience of the bombing of the city and, in 1942, joined the Royal Army Medical Corps in Denbigh, where he undertook non-combatant duties and learned to box. Tall, lantern-jawed, and broadshouldered, he had handsome features marred only by a flat nose which many thought he had acquired in the ring, though in fact it had been broken during a cricket-match in Pwllheli. He spent the rest of the War at a camp for Italian and German prisoners in Hampton Lovett near Droitwich in Worcestershire, in some of whom he detected those human qualities which made him love his fellow men. He was especially fond of Liverpudlians, among whom he had been brought up, and, as a Welsh nationalist, was never anti-English in his outlook.
Even before the end of hostilities, he had begun the political activity to which he was to devote the rest of his life. In July 1945 he was given leave to work for Plaid Cymru in the Caernarfon Boroughs, Lloyd George's old seat, where he put into practice the financial skills he had learned at Martins Bank. Soon afterwards he was transferred to the bank's branch in Newport, Monmouthshire, but stayed there only two years before finding employment as a district manager with Silcocks, the animal foodstuffs company, which promptly sent him to work in Cardiganshire.
It was not long before "Roberts Silcocks" was asked to stand as a candidate in the county election of 1952, in which he was duly elected. Although he made no secret of his nationalist affiliations, starting branches of Plaid Cymruup and down the county, he sat as an independent member in the Cardiganshire tradition, which was abandoned only in the 1970s. At the age of 33 he joined a council where the average age was 65, thus coming up against some of the more entrenched members of the Dinosaur Tendency in the ruling Labour and Liberal parties.
He nevertheless succeeded in introducing important initiatives in the public use of Welsh in the council's business and in the teaching of the language in the county's schools.So began a distinguished career in local government which was to last unbroken for more than 40 years. He served on the Cardiganshire County Council from 1952 to 1974 and, after the reorganisation of county boundaries, on Dyfed County Council, of which he was chairman from 1973 to 1976. Having left Silcocks in 1966, he and his wife, Margaret, kept a café and crafts shop in the small village of Synod Inn, a few miles south of Aberystwyth, which served not only as a petrol-pump station but as a meetingplace for Plaid Cymru members travelling up and down Cardigan Bay. He also played a part at a national level, standing as the party's candidate against Labour's Megan Lloyd George at Carmarthen in 1959, serving on its National Executive for many years, and helping to organise its campaigns in the by-elections in the Rhondda and Caerffili in 1967 and 1968, at which Plaid Cymru came near to winning those Labour seats.
Such was his reputation as a sensible, capable and good-humoured man, he was asked to serve on many public bodies - more than 40 in all.
They included the Welsh Folk Museum, Dyfed-Powys Police Authority, the Welsh Joint Education Committee, the Court and Council of the University of Wales, the Welsh Theatre Company, the Welsh National School of Music and Drama, the National Museum of Wales, the Wales Tourist Board, the Welsh National Opera Company and the Welsh Water Authority. He was also High Sheriff of Dyfed (1982-83) and a leading member of the Congregationalists in Cardiganshire. Having turned down the offer of an honour from the Queen on the grounds that a Welsh nationalist should have no truck with royalty or empire, he took particular pleasure in being admitted to the druidic order of the Gorsedd of Bards in 1976, which he thought was honour enough for a Welsh patriot devoted to the public life of his country.
Hywel Heulyn Roberts, county councillor: born Liverpool 16 March 1919; married 1944 Margaret Davies (died 2004, one son, two daughters and one daughter deceased); died Tregaron, Ceredigion 30 April 2010.