Went to B&Q, got some MDF cut to size and now the footstool has a new lid. Entering Ship of Theseus territory here. Just need the constant rain showers to stop here so I can sand and paint it.

Test fit of fabric lid supports. Was going to use a gas strut support I got but it's too big so went back to a fabric solution. It's a bit rough at the moment, but I'm going to redo it once I've sanded/painted it.