The first bridge between Runcorn and Widnes which allowed carts etc. to cross the Mersey without getting wet.

This view is from the north side of the bridge taken from Widnes with Runcorn on the opposite bank.

The message reads:-

Dear Ernest
I am writing as promised but excuse the PC as it is one out of the shop.
Hope the weather is not too cold for you it is beastly here
Alice

The "upside down" writing reads:
I have not told H as you think(?) hope to see you Sunday.