Crumbs!
Google groups just managed to retrieve a thread!
WRT the OPs post.
Electrical inspection seem to be the in thing for surveyors/lendors to ask for at the mo, (Though ours only recommended we have it done rather than requiring it). When we bought a couple of houses back in the 80s it was damp proofing/woodworm they wanted checks & assurances on.
Why should the seller pay anything for bringing the installation up to the latest regs? I certainly wouldn't, any more than i'd pay for the purchaser to install new wallpaper or carpets. You've made an offer to buy the house as it is, not as you might like to have it in the future.
Also if a prospective purchasor was honest enough to tall me that they wished to have an electrician take every bit of my installation apart to check it over, i'd tell i'd be happy to have it done anytime after completion! Such an inspection takes a long time (all day for a 3 bed terrace) and is very disruptive if you are in (or in our case my wife and young child were in).
Coming back to technicalities, if you go ahead and buy the house I would propose having an electrician inspect it with a view to having a split load consumer unit with RCD and MCBs fitted together with any replacement fittings and/or new circuits.
This is just what we've had done at our place. Only downside is the lighting mcbs tripping everytime a light bulb goes (and there's lots of them to go).
You can get manage with one or two rings, but if you can easily separate off the upper floor(s) if it isn't already, and or add a separate ring for the kitchen then that would be good.
WRT the poster who complained that the whole house RCD was tripping whenever a bulb blew, is this normal behavior for such an installation? If so, is it just where earthed metal light fittings are used? We used to have a whole house ELCB, but it didn't trip when lights blew. I can't think that we've had an overcurrent fault on the new system to know whether the new RCD would let go or not. I did once tough a live wire on what I thought was an isolated socket, and was a little disappointed that disconnected myself before the new RCD did (Well, I was glad to have disconnected, but surprised the rcd didn't trip).