On 19 November 1562, aged 20, he was in an affray in the Strand in the company of his cousin, Nicholes Specott, gentleman, with Lewis Lloyd and Edward Horseman, their attendants. Upon encountering Sir Edmound Unton, Fulke Greville, Robert Bannister, gentleman, and Thomas Allen, yeoman, (with their servants), Grenville ran Robert Bannister through with his sword, then left him to die. Grenville and company were outlawed for three months and then pardoned for public duelling and manslaughter, just in time to resume his seat in Parliament.