Guest sat as a member of Parliament for Honiton from 1825 until 1831 . It was largely through his influence that the new parliamentary constituency of the Merthyr borough including Aberdare and Vaynor ) was created. He was returned unopposed in 1832 (as a Liberal and Free Trader ) as the first M.P. for the Merthyr borough , and kept his seat until his death in 1852 . In 1838 he was created a baronet .
Though brought up as a Wesleyan Methodist , Guest erected Dowlais church in 1827 and contributed £3,000 towards the expense, and gave £250 towards the new church of S. Davids at Merthyr . He was the chief promoter of the Taff Vale railway and became its first chairman . He and Crawshay Bailey were the chief promoters of the Aberdare valley railway which was taken over later by the Taff Vale Railway Company . He opened a bank at Cardiff with a branch at Merthyr in 1823 , but these were closed in 1825 because of Government opposition. At Dowlais he established and continued a warm supporter of a savings bank . In 1830 he was elected F.R.S. ; in 1834 he became an Associate of the Institution of Civil Engineers .
In 1837 Guest presided at a meeting of the inhabitants of Merthyr called to consider the propriety of obtaining an act of Parliament for the incorporation of Merthyr . The town had, however, to wait nearly seventy years to see this ambition realized, its first mayor being elected in 1906 . Guest was elected, 1 April 1837 , as the first chairman of the Merthyr board of guardians . After an inquiry at Merthyr , conducted by an inspector of the board of health into an application by Merthyr to be allowed to adopt the Public Health Act of 1848 , and after seeing the disastrous consequences of the second visitation of the cholera epidemic in 1849 , the Merthyr board of health (the precursor of the Merthyr Urban District Council , and, later, the Merthyr Corporation ), was formed in 1850 , when Guest was elected as the first chairman . Merthyr citizens held meetings to take steps to erect a town hall worthy of such an important centre of population during May 1850 , canvassed the district for donations, and Sir John Guest promised £1,000 towards the funds.
During the later years of his life he removed to Canford Manor , Dorset , where his descendants have since lived, but as death approached he returned to Dowlais , the home of his birth, youth, and activities, and there he d. 26 Nov. 1852 and was buried.
Watkin William Price, M.A., (1873-1967), Aberdare
Published date: 1959