Granborough bridge. But what's that, bottom left?

What’s this strange metal object built into the bridge? It’s an Ordnance Survey Bench Mark, and it was put there for map making. The number 1967 isn’t the year it was installed; it was built into the bridge in about 1914.

The OSBM.

There are thousands of these bench marks in the UK, numbered in sequence on long surveying lines across the country.

Visible from the Winslow road several miles away, it looks like a huge Norman castle, set against the background of the Chilterns. But instead, it’s a 1960s building right in the centre of Aylesbury.

The King’s Head in Aylesbury dates from 1455. Coaches would go through this arch when they arrived at this inn.

How do you recognise the old 18th Century turnpikes; the first decent roads to be built in Britain since the Romans left?

It’s quite easy, and there are a few ways to do it.

The first clue is the presence of milestones. If you see a milestone, you are almost certainly on a turnpike. Anciently, a turnpike was a horizontal wooden boom that turned on a vertical pivot, placed across the road until the toll keeper got your money. It came to mean the whole road.

This mile post is in Little Woolstone, in the middle of Milton Keynes.

I've been a bit behind with my blog posts recently. Sorry about that, folks! I've had to deal with family stuff and illness. I hope to bring you this week's post later today.