Sir - There is - at least for the time being - a non-extinct Post Office on the corner of Walton and Great Clarendon Streets in Oxford.

Outside is a postbox on which a new notice reads: "Change to final collection time from this postbox. In order to provide our customers with the best possible service we are revising collection times from postboxes. From 21st April, 2008, the latest collection time from this postbox will be brought forward from 6.45pm to 5.30pm."

So, for example, office and shop workers posting their first-class letters after work in the hope that these might be delivered the next day will have to forget about it!

By a perfect coincidence, just as I was copying this notice down in order to write this letter to you, a postman turned up in a Royal Mail van.

He hadn't seen the notice before. Like me, he thought "the world was turning upside down".

Julian Dare, Oxford