Anna is so right. Abandon the gypsum and use the real stuff. Here's
a couple of firms that will supply goat hair, lime putty and
everything else you need to fix a lath and plaster ceiling the proper
way. Order on line from Womersleys or Mike Wye:

http://www.womersleys.co.uk/acatalog..._plasters.html
http://www.mikewye.co.uk/

Get more advice from Perdiod Property UK Forum. Lots of experts
willing to share their knowledge about looking after old houses
properly hang out there.

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