It is a straight flight with a dog-leg, the last few steps at right angles. Prising out the boards looks do-able, so the bottom of the string furthest from the wall won't be holding the weight?
Thanks for the quick reply!
Moved into a house which has had woodworm in the suspended ground timber floor, mostly in the kitchen but some of hallway too. Half of the kitchen subfloor is broken-up chipboard anyway, so just replacing the lot.
Originally there would have been 170x22mm finished size T&G timbers running all...