The corrugated iron roofs of most of the shelters were collected by the authorities at the end of the war. Other shelters which were no longer needed were sold to the householders for £1 each (the equivalent of around £35 in 2015). These were often dug up and re-erected above ground, fitted with proper wooden doors and used as workshops or garden sheds. Much of the corrugated iron was also re-used by farmers.
Not all the sheds, animal shelters etc. that survive until today were once Anderson shelters but you can look at the following photos and decide which might have once been shelters, and which were built with new metal after the war.
Here is a photo of an post-war 'prefab' estate showing a re-erected shelter to the left of the picture, and another at the back of the estate.
And here is a close-up of such a shelter:
Amazingly, some of these re-positioned shelters are still in good condition today. Here are some photos:
These are of a shelter in Kentish Town ...
And here is one in Whetstone, North London ...
And here is one in Edinburgh, before it was dismantled and then rebuilt by Joe McGuigan.
I am grateful to Phil Hall for telling me about this structure which he found in a wood south of Westerham in Kent. It is about 4 metres long and has 7 sheets of corrugated iron on each side, all set into a concrete base. It was presumably once used for agricultural purposes but is still in amazing condition given its age - and the fact that it is now supporting a rather heavy tree! Even the Trademark Staley maker's marks are still very clear.
(The photo was taken in 2015. The Ordnance Survey grid reference (according to my GPS) is TQ 4534 5296.)
Neil Hannant uses recycled sheets of corrugated iron to provide covers under which his pheasants can lay their eggs:
Here are two photos of a rather smart shelter, now on rather than in the ground, but still in its original garden in Bristol.
This structure is in Hastings:
It is very similar to this one, advertised as a pig pen on eBay in 2017. Note the lifting handle in each corner and the short flat roof section, with no central bolts. The ends are flat sheet & there is what looks like a riveted angle trim all round between the ends & the curved sides/roof.