Thanks everyone for your comments. What with them and the FAQ and
heatwen.com I have just had a fun evening reading up on heating
systems. The outcome is that no way will I fit a suitably sized
standard thermal store in the allocated space. There is a 'lying on
its side' version available at a price, but before resorting to that I
will cudgel my brains to think up another place with more headroom to
put the thermal store. I suspect my system might end up looking
remarkably like NP's

On the bright side, having removed half the heating system there is
now plenty of room for the loft ladder

Anna
~~ Anna Kettle, Suffolk, England
|""""| ~ Lime plaster repairs
/ ^^ \ // Freehand modelling in lime: overmantels, pargeting etc
|____| www.kettlenet.co.uk 01359 230642