Success!

We finally managed to get into the boxed-in cistern today.  We didn't have particularly high hopes for getting the worktop off the top of it, especially having tiled around the stack a few years ago, but Tim very carefully worked at it and managed to do it.  Phew!  He fixed the leak too (some numpty had fitted the overflow pipe without a washer, so when the water reached the bottom of the overflow pipe it just leaked out the side), so all in all a big relief.

Tim did most of the work, and I helped out where I could, but I still ended up feeling completely exhausted.  Glad to have it sorted though.