When Jeffrey Archer suddenly announced his decision to stand down from Parliament due to financial problems, Brotherton was selected as the candidate for Louth in the October 1974 general election.
Early in January 1976 he challenged James Callaghan, then Foreign Secretary, to substantiate Sheila Cassidy's claim that she had been tortured in Chile before making any protest to the Chilean government.
In March 1976, he pressed the issue of a member of the House of Commons catering staff who had been found to be a supporter of the Provisional Irish Republican Army, calling for stricter vetting.
Brotherton supported the call for a boycott of the 1980 Moscow Olympics, and voted against a rise in petrol duty which was proposed by Geoffrey Howe in the 1981 budget.
In March 1982, when the Adam Smith Institute rated MPs according to their tendency to vote for individual freedom, Brotherton and his Parliamentary neighbour Michael Brown topped the list.
In December 1982, Brotherton (a strong opponent of wasteful spending) was embarrassed when he missed a rail connection and then asked three police cars to drive him from Newark-on-Trent to a charity event in Grimsby.