Thank you all for the replies. It's definitely not a flying model, just static display. It could well have seen too much sunlight in the past - it was used as a toy by my cousins for some years before it was rescued, so the whole thing is pretty badly damaged and it's going to be a long haul to get it anywhere near presentable.
If anyone can point me at a guide on how to do this smash moulding, that would really help. Is that likely to have been a technique that would have been used with the materials that were available 75 years ago?
My dad is convinced that his dad scratch-built this model and two others, but I thought it must have been built from the Airfix kit of the time. Having dismantled it a bit, I'm still not sure. Some of the parts I've removed were made from nails with the heads cut off and I can see marking out lines on unpainted sections - suggesting scratch-built. But then I look at the canopy and a mechanism for locking the undercarriage up or down and think it must have been a kit.