A bit of a ball-ache, this - front door is secured by a mortice
latch/lock but is ever-so-slightly out of position, so that the latch
will only engage if you either slam the door, or close it fully and
gently, and apply a sudden 'shove' to get the latch to click into place
(something that SWMBO's not strong enough to do). In other words, the
striker plate needs moving no more than 1 mm outwards from the frame.

There's no way I'd able to fill and redrill the screwholes in the frame
effectively (the old and new would overlap). Suggestions, please?

Thanks
David