i moved house in april i had a good credit rating before i moved; since i moved my bank wont give me a credit card,

I think it might be somebody who previously lived at your new address and had a bad credit history. I would suggest signing up to one of the current free trial offers to get your credit rating. You may find your name is being linked with somebody who is nothing to do with you. Just don't forget to cancel before they charge you at the end of the trial period.

i quite agree, get a credit check and find out if there is an adverse credit history associated with the address.

Have you updated your address on the electoral roll? May be worth checking.

There are so many reasons why your bank may have decided not to give you a credit card though (you may not have been seen as profitable enough!) so I'd say check your credit rating like the others said & take it from there. Perhaps ask your bank too.

1) Check your credit report - 30-day free trial at credit-expert.co.uk
2) Get on the electoral role - Go to your council's website

Ah, the black art of credit scoring! First to clear up a couple of common misconceptions:

1) "I've been blacklisted." No. There is no such thing as a property blacklist, or indeed, any blacklist! This was a term used to explain credit scoring in laymen's terms, but there is no central list of addresses with "don't lend to these people" written on it. Secondly:

2) "I can't get credit because the guy who lived here previously defaulted/my lodger was declared bankrupt." Again, no. I lived in a shared house of seven people whilst at University (which had seven different people the year before, and seven different again the year after). Some of them were able to get loans, some weren't. The only reason I wasn't able to was that I'd defaulted on a credit card. There are only two ways to financially link yourself with another on your credit profile:

a) Get a joint current account.
b) Get a joint mortgage.

So, you haven't done anything that will negatively affect your score, however, you have stopped doing thing that would normally positively affect your score, ie

a) Staying at the same address for a long time
b) Being on the electoral role (both show stability)

I could write all day about how a financial institution decides on whether or not to provide you with a service or product, but I won't. For now, your action points are:

1) Check your credit report. You can normally get a 30-day free trial with Experian at credit-expert.co.uk, and scoring then costs around £6 (just remember to cancel it!)
2) Get on the electoral role. Go to your council's website (usually www.la.gov.uk where 'la' is the name of you local authority ie www.sheffield.gov.uk) and search the page - it should be fairly prominent at present with elections coming up. Note that if you're living in a shire county, it's the DISTRICT council you want, not the county council (ie Aylesbury Vale, not Buckinghamshire)