Hi Ste,
Thanks so much for your very informative advice. Yes, my garden is pretty much in the open as well, which could be part of the problem. Apart from the lovely big tree, there isn't much else around in the way of parks or bushland. Downside of living in suburbia, I guess.
I've been living in Swindon for four years now, and come to think of it, the only birds I've ever seen anywhere in the town are crows, seagulls, pigeons, magpies, starlings, blackbirds and thrushes. Is it that the larger birds (like crows) frighten off the smaller birds or is it definitely the location, ie not enough parkland nearby. Sorry, my knowledge of wild birds is not very good. I am from New Zealand and we don't have the same birds as you have here, apart from the introduced sparrows, blackbirds, etc.
I will definitely take your advice and put up some feeders in the tree and see what happens. And will certainly let you know if I attract any new birdlife.
Regards, Snowhound