William Stanley Russell Thomas (5 February 1896 – 21 March 1957) was a physician, barrister and Welsh Liberal politician who served as a Liberal National Member of Parliament.

Thomas was born at Talgarth.^[1] He was educated at Brecon Grammar School, Christ College, Brecon, and Queens' College, Cambridge. He qualified MB BChir at Guy's Hospital in 1919 and was awarded the Treasurer's gold medal in clinical medicine.^[1] He held resident appointments at Guy's Hospital and Sheffield Royal Hospital and was assistant medical officer at West Riding Asylum in Wafefield. He was called to the Bar by Lincoln's Inn in 1930.^[1]

Thomas advocated for animal welfare. He was a council member of the RSPCA 1943–1954 and chairman 1951–1952.^[2]

He died at his home in Warlingham, aged 61.^[1]

He was Liberal candidate for Ilford in the 1931 election. It was a promising seat which the Liberals had nearly gained from the Conservatives in 1929. At the 1931 elections, the Liberal party was split into three groups and Thomas remained with the official Liberals under Sir Herbert Samuel, in support of the National Government. He finished third in Ilford, just behind the Labour candidate. He remained loyal to the official Liberal party when it left the National government in 1932.

Despite his poor showing at Ilford in 1931, for the 1935 election he was selected as Liberal candidate in the promising constituency of Aberdeenshire Central where the Liberal in 1931 finished a close second behind the Conservative in a two-party contest. However, in 1935, the Labour party intervened and in a three-way contest Thomas finished third, again just behind Labour.

His next attempt to enter parliament was also in Scotland at the 1936 Ross and Cromarty by-election. In 1935, the Liberal National candidate was re-elected unopposed. When the by-election came around, a minority section of the local Liberal Association wanted a Liberal to stand and were unhappy when the majority decided to support a National Labour candidate. The Scottish Liberal Federation persuaded Thomas to stand as a Liberal candidate.^[4] However, the result was a disaster for Thomas as he finished fourth.

Following this disappointment, Thomas decided to switch his support from the official Liberal party to the Liberal National party.

His connection with the Liberal Nationals was far more rewarding when he was chosen as the National government's candidate for the 1940 by-election in Southampton. By then, a war time electoral truce between the main political parties was in operation, so Thomas was returned unopposed. At the 1945 General election, Thomas sought re-election as a Liberal National candidate in support of Winston Churchill. Southampton was a dual member seat and he ran in tandem with a Conservative against two Labour candidates and a Liberal. However, he lost his seat and finished fourth.

Thomas contested Middlesbrough East in the 1950 general election, however, this time not as a Liberal National but as an official Liberal candidate. He came third with 10% of the vote.

Despite his Welsh heritage, none of his previous electoral challenges was in his native Wales. However he was selected as Liberal candidate for Brecon & Radnor for the 1955 General election. Having been raised in Brecon, he might have had hopes of winning. However, the Liberals had not contested the seat in 1951 and in 1950, their candidate finished a poor third. The 1955 elections represented the lowest point in the fortunes of the Liberal party and Thomas was to finish third once again.

This was to be his electoral swansong.

1. Times Guide House of Commons 1955

• Hansard 1803–2005: contributions in Parliament by William Stanley Russell Thomas