Possible Mortgage Lenders for bad credit history

Does anyone have an idea which lenders are more lenient and more likely to offer a mortgage to someone with a poor credit history?

The persons in question don't have a terrible credit history but have some credit card debts and have been turned down by Santander.

I know a mortgage broker could help but in the absence of a broker does anyone know which lenders may be more likely to consider offering a mortgage. Are smaller banks/building societies more flexible? They obviously don't want to keep applying through trial and error and getting turned down as they know this will further impact their credit rating.

Thanks