My husband arrived home with this little bird yesterday. We believe that it had fallen from its nest. He waited a long time but no adults (birds) appeared. He was in two minds to whether to remove the bird but it was in an area known to have rats by a pond, foxes and dog walkers.
The advice from the rescue centre was to give it water and scrambled egg. It was comfy overnight and settled in a roosting position and was tweeting this morning but did not look distressed. We took it to a rescue centre and they put it with another young magpie and they were hopeful that the pair would do well and be released together when the time is right.