I also fixed a door and its strikeplate problem for a daughter in London.
What could have been a straightforward 5 minute job as usual blossomed:
Sliding door is for an outside cupboard(!) but under cover behind parking spaces.
There are five, one for each flat, only one original door working, one changed with hinges and hasp padlock;
anyway daughter had found a workman changing clothes inside her cupboard so...
Vintage clawbolt lock from 1973, keys lost by previous owners. I bought an exact 3 lever replacement for £50, nevertheless happy day.
Cleaned the wheels and runner with wd40. Smooth.
Fitted new expanding clawbolt lock easily.
And then what I'd expected,
a pretty stunning misalignment due to the frame having been bumped by a car.
"Got any tools?"
Had to chisel out (blunt vintage & using an antique club hammer) the wooden frame to fit strike plate half an inch higher; file (mini craft set) the inner rectangular hole of the strike plate to widen the tolerance for the expanding lock; and saw (junior hacksaw) the old metal strike plate and use the two parts to raise the new brass one from the frame.
Two and a half hours of expert improvisations (faffing about
)