I would say it didn't sell and he should be happy to take 3800 as it is not far off.

Stick to you guns, tell him your keen, have the cash but are actively looking and WILL be buying something in the next week.

Remind him you have a lot of travelling to do and that the most you can go to is £3800 and that that is a genuine offer. Leave the ball in his court and stand firm.

If he waits over a week and then calls tell him your offer is £3500 lol!!