Although morally confusing, this is also excellent.
My solicitor told me not to worry and to proceed nonetheless at the price they wanted. I obviously informed him that I didn't have £20k and he told me not to worry.
On the day of exchange, my solicitor and I chipped the price by £20k and told them that because it had taken so long to process, values had dipped and that the original price was the only one I was prepared to pay.
Although morally confusing, this is also excellent.