vampirequeen, great name!
Your story reminded me of when my son was little and he had an imaginary friend called 'green man'.
According to my son, the man would come and talk to him when he was in bed and tell him stories etc, this went on for quite some time from when my son was 3/4 to about 6 years old.
Anyway, one day I took him to a local museum and we visited the transport section. Inside was a WW2 Fire engine...the minute my son saw this he became really excited and started to tell me about his friend 'the green man' and that he had one of them, he also started to talk about the bombs and the big ship that his friend had seen.
Spooky.....my grandfather (who I idolised) had been a fireman in the war and during the blitz in Liverpool had been present when the SS Malakand was hit.
To the best of my knowledge, nobody had talked about it to him and he didn't really know. My grandfather died when I was in my early teens.
I can't explain it and my son's memories of it all are very vague.