We also bank with Lloyds wonderfull TSB. They seem ok and we got 2 years free banking for a business account.
Before that we were with Abbey National untill they got a bit funny about the number of cheques each week.
Before that HSBC (the Midland).
When our free banking runs out I will find another bank with an offer of 'free banking for business accounts' and change our account name yet again on the pretense of being a new business. Our actual trading name remains the same, it's just who the cheque is payable to that changes. Our business name is 'Cops' but our account name is 'Brighton Shines'. It's never caused a single problem.
As far as I'm concerned, when it comes to banks I will lie through my teeth to get free banking.
As Tosh wrote, you don't need a separate account but it does make things simpler though. Well for me it does.