Withdrawing mortgage offers above 80% is not true, tawse57. We've been approved for an up to 85% mortgage, in writing, by HSBC. You can get higher ratios too, but the interest rates jump with them. So it could be that affordability is the issue.
Regarding gazundering and gazumping, some people are always going to try it on to get a better deal. Unfortunately, because of the way property sales work in this country, there's not a whole lot you can do to stop it.
But that might not be the situation in this case. Perhaps the buyer that dropped out has had a family tragedy? Perhaps they were made redundant? We just don't know the situation.
Besides, I'm not sure how knowing any of that is going to help the Op not experience this situation again - since the chain break was several houses down the chain from their own and therefore almost completely out of their control!
Are people meant to ask potential buyers at time of offer whether their buyer's buyer's buyer is definitely able to proceed, can guarentee they're not going to change their mind and look in their crystal ball to make sure they don't have any calamities approaching?
I'm sorry to hear your chain collapsed, Minstrelsaremarvellous. Hopefully someone will come along soon and get things moving again! Is the rest of the chain holding together, or has the whole thing come apart now?