Bugged right, gotchas everywhere.
RAF colleague did walkround - found prob during startup - went for coffee in line hut whilst ground engineers fixed it.
Climbed in - took off and couldn't retract gear.
Landed back and found nose lock and one main gear lock still in position.
Ground crew had, perfectly sensibly, refitted locks before troubleshooting.
Neither he nor his FE had done another walkround.
Yer learns about flying from that.
Main gear locks on that aircraft, which SHOULD have been clamped in position but were often just laid on top of the struts, weighed, and I'm guessing here, about 30lbs.
Something will go 'ding!' against a plough one day.
Poor chap was killed in a Vulcan air display. RIP Simon.