Fisher, who was now the chief citizen of Warwick, was secretary to the Duke of Somerset, protector of England.
Towards the end of June 1548 he was commissioned by Somerset to travel north to Francis Talbot, 5th Earl of Shrewsbury and William Grey, 13th Baron Grey de Wilton, with instructions for the defence of Haddington, and for the other manoeuvres of the army in Scotland.