Seeing this mission listed made me feel like a lemon, after all I'd done the original fix on the old toilet seat a couple of months ago and it obviously needing doing again now. Pah. Anyway, this time Mrs L had bought a new toilet seat, so the problem with the old fixings last time (and why it failed) went away. Nice simple, literally-5-minute job to install the new one. Easy peasy, lemon squeezy.