So, here's a list of many of the things on display in the Old Street Post Office:
Credit card applications
Mobile phone top-ups
Invitations to join Napster
Post Office service level metrics
Internet (ISP) CDs
Numerous forms for HGV licences, postal insurance, TV licence etc.
Coloured pens and other bits of stationery
Insurance deals (Home insurance, travel insurance, car insurance)
Adverts for foreign exchange
Pamphlets on claiming benefits
Pamphlets on guaranteed equity bonds
Pamphlets on child trust funds
Pamphlets on National Savings
OK, you get the idea. You probably have also spotted the item that is conspicuous by its absence. A booklet or wall chart detailing how much it costs to send a sodding letter. Seeing as about 80% of the people who go into the Post Office do so in order to post things (the clue's in the name of the building), I regard this as a major oversight. So now, as well as carrying around various denominations of stamps I also have to carry round a sheet of postage charges.
One tbing I did notice was a gizmo for measuring the size of a letter. I did hear rumours of the P.O. switching to charging by the size of a package rather than weight but so far as I know this policy has not yet been implemented. When it is, I am confident that one will be able to find out the size of one's letter but not how much to send it.
Here endeth the Victor Meldrew moment.