John Lewis was never quite elected as MP for Radnor. In 1768 an election petition saw his opponent Edward Lewis sent to parliament in his place. In 1774 he was declared the winner even though he had polled 201 votes to Edward Lewis's 619, the returning officer having ruled out the votes of the non-resident burgesses. Another election petition saw the result reversed. In 1780 a double return was made of both men, and once again Edward prevailed.

John Herbert Lewis, MP for Flint Boroughs/Flintshire (1892-1918) and the University of Wales (1918-22) was an associate of Lloyd George in Cymru Fudd, a group within Liberalism advocating greater independence for Wales.

John Lewis, MP for Bolton/ Bolton West (1945-51) ended his career ignominiously, having hit a policeman with his car on the way to the Commons, and became embroiled in an argument about the use of parliamentary privilege to defend himself. Further JLs were MPs for Marylebone (1861-74) and Devonport (1868-74).