Helen Mayson wrote:

Hi Roger,

I've had a go at this but gravity doesn't seem to be my friend - it
keeps catching on something in there!

If you are hitting it from above, all you are doing is forcing it deeper
into the hole. Support the bed with about 2 foot (600 mm) above ground,
with the screw point up and use a soft faced hammer from underneath. If
you don't have a soft faced hammer, find a piece of softwood and place
it against the bed and hit that. This might just be enough to get it out.

Dave