OK, here's the deal.
The house Sharon and I want to buy is £130,000 (it was £135k but they accepted our offer of £130k).
Our house is on the market at £90,000.
I can afford to increase my mortgage by £40,000. So it's all good.
Except that the highest offer we've had on our house is just £86,000. We're £4,000 short (not to mention stamp duty and fees).
The people whose house we're looking to buy have offered to knock a further £500 off but that still leaves us out by £3,500.
Bugger!