My experience with HSBC was quite painless. The suit probably helped, but I didn't go in with a written business plan. I was required to talk about myself, the training, job prospects and repaying the loan. Once I told them that the equity in my flat exceeded what I wanted to borrow they were all smiles. The sting in the tail was that I had to pay £190 for a valuation by one of their panel-nominated surveyors.
The Manager told me that as far as he was concerned loans in excess of £15k require some form of security - don't know if this is general policy though.