Thank you all! @OrangeJeans the sand in the long jump is, in fact - sand!
I store it all in my shed. It's kept in plastic storage boxes arranged according to theme (and labelled) on a set of shelving which runs along one side of the shed.
Some of it originally belonged to my ds, who played with it a lot from the ages of 5 up until early teens. But he is 23 now, so I have taken over his collection and added to it over the last few years.
I try not to stand on it, as some of it can get broken that way. I remember several years ago we had to superglue Bossy Ross's leg back on after ds's grandad accidentally stood on him! 