Would they also be liable for other losses in the chain? For example if A is selling their house to B who is selling their's to C etc. If A pulls out then B will have to pull out, through no fault of their own, which means that C could sue them?
Not really, you generally can't sue someone for incidental losses. Otherwise if a driver somewhere caused a road accident that delayed your bus to an important meeting, which resulted in a substantial financial loss, you'd be able to sue that driver, and so on.
But as said it's a bit moot, individuals generally don't sue one another, there's little court time and it's ruinously expensive. When the lovely people we bought how first off decided to trash it before leaving, we assumed we could sue them, both sets of solicitors laughed sadly
well you could... (in the end their solicitors gave us the money, I assume they wrote it off, or chased it up themselves, though I suspect they also wanted to cut their losses with those two).
These are systems that were built for transactions that could be completed quickly and had a total value of <£10k, now extrapolated to long drawn-out processes for transactions for hundreds of thousands – if not millions – of pounds.
We're vaguely looking, and indeed, in the more rural realms hereabouts there's not much about, a lot of people are decamping from London for homes out in the country. I can't complain that's what we'd be doing. We did wander by a lovely oast the other weekend. Let's buy that, we asserted. Then we looked at the price, which had sallied far north of one million British pounds.