After surviving a recent vote of no confidence, the PM finally bowed to pressure from his own party and resigned, giving a speech outside No10 Downing Street at lunchtime.
The race for the top job will now begin with a new PM expected to be appointed in the autumn.
Here we look back at some of Boris’ visits to Lancashire, including Preston, Blackpool, Leyland, Burnley and Accrington.
1. Jog on
Boris Johnson runs on Blackpool Beach during his time in the resort for the Conservative Party conference earlier this year. Photograph credit: Conservative Party/ @Conservatives Photo: cp
2. Platform PM
Boris at Preston train station. Picture by Andrew Parsons CCHQ / Parsons Media Photo: parsons
3. The eyes have it
Boris Johnson meeting a student at Blackpool and The Fylde College Photo: nw
4. Hair today, gone tomorrow
Boris with a student at Blackpool and The Fylde College Photo: nw