Llewelyn was
High Sheriff of Glamorgan in 1878 and Mayor of
Swansea in 1891. In March 1888, Llewelyn contested the
Gower by-election as a Conservative candidate. The Liberal ranks had been affected by divisions over the choice of candidate and Llewelyn ran a strong campaign. Unusually for a Conservative candidate he held meetings in nonconformist chapels, including one at Zoar,
Ystalyfera which was said to have been well attended by the working men of the district. Llewelyn polled well although narrowly defeated by
David Randell. In
1889 he was elected as one of the first members of
Glamorgan County Council and was immediately made an alderman, to which role he was re-elected in
1895. He was created a
baronet, 'of
Penllergaer in
Llangyfelach and of Ynys-y-gerwn in
Cadoxton juxta Neath both in the
County of Glamorgan', on 20 March 1890. In 1892, following the death of his uncle,
Lewis Llewelyn Dillwyn, Llewelyn was adopted as Conservative candidate for the
Swansea Town constituency but was defeated by
R.D. Burnie. However he reversed the result three years later when he was elected Conservative MP for
Swansea in the
1895 general election, but lost the seat in 1900. Llewelyn's connections to sport included the position of captain of the South Wales Cricket Club and in 1885 he replaced the
Earl of Jersey as the president of the
Welsh Rugby Union; a post he would hold until 1906, when he was replaced by
Horace Lyne. Lyne himself stated that 'they (WRU) had been singularly fortunate in getting a gentleman like Mr J.T.D. Llewelyn to act in that captaincy'. ==Family==