Hi,
With the recent 'availibility' of accessing your credit report it makes you think you have a little more control over finances which when required for loans, mortgages etc, gives you the impression you have more of a chance of being accepted. For the 'most' part that is true - except for when you get seemingly inexplicable actions like some of the ones described here in the replies!
However, there are some aspects which aren't so immediately obvious but can and do affect your credit score negatively.
having financial 'links' to someone with a seemingly worse or bad history will impact you quite a bit, in many instances the person with that less than good record will have made various 'attempts' at obtaining credit and been refused. The number of times applied for credit is recorded as well - they 'dont like' people applying for credit here and there as to them it shows lack of discipline with money and hence their lending may be at risk later on so better to refuse it now.
Late payments are something they really 'hate' - it marks you down, even a single missed payment - 2 and you're asking for trouble, 3 late payments and that it - mark down time. The agencies also look at your existing levels of debt and with who they're with - so if you have a mortgage, bank loans and credit card loans here and there you're much riskier than say someone with a couple of credit cards and a mortgage say. If you have Credit cards you dont use, close the accounts, it looks 'better' on your credit report.
Address 'usually' doesn't come into it, as loans and debts are recorded against an individuals name rather than their address. With how fluid movements are the emphasis that used to be placed on address is less so nowadays in terms of your credit report itself. I know many places always say 'at least 3 years at this address' and for this board which deals with people in from abroad thats frustrating - hence the excellent workarounds suggested to start to build credit here when initially arriving here.
On a broader and larger scale - over the last 5-6 years or so, money has literally been given away and thrown at people becuase of it's 'apparent' cheapness. Many people took it up and played right into the UK 'Trait' of keeping up with the jones' etc (thats wy the UK on its own has more credit debt than ALL other European countries COMBINED!) and are now finding it has to be paid back you know! - end result, non and missed payments, more bankruptcies (sp?) and bad credit reports.
It's come to the stage where in order to be able to get what you'd like in life in the UK, the basics or more of the fundamentals are harder to obtain becuase of all the credit problems etc, so many people are 'risking' having a bad credit rating in order to get that mortgage or loan etc just to be able to get a house, then having to scrimp on other aspects to run that household and usually important stuff like insurance (remember the floods of 2007, and how many uninsured there were) is bypassed so that the having a nice car outside or the holiday abroad each year can happen.
I'll stop there on those aspects!
to 'help' as best you can with your credit ratings
1. Pay your bills on time, every time each and every month *VERY important*
2. Dont make too many applications for credit in relatively short spaces of time.
3. Save as much money as you possibly can to help with purchases instead of sticking them on credit.
4. Any credit cards, store cards you dont use - close them
If you want to try and get (for whatever reason) credit and are borderline - carefully analyse the risks of losing your credit rating for while and build it up later in order to get what you need now (tends usually to be large things like mortgages, business loans etc)
There's much more of course but I can't sit here all day - plus probably wouldnt all fit in this reply! but generally the above and the other responses are the deal with credit history/reports etc and I agree, it's extremely frustrating when things happen which dont appear to follow the 'rules' as it were.
Hope the above helps!
Cheers, DtM! West London & Slough UK!