TSB current account pays 5% on balances up to £2,000. Using your spouse that means £4,000 at 4% net. You only need to pay in £500 per month (and you can then immediately switch it back out).
The balance transfer fee is a one off of, say 2.5% for a 2 year period compared with over 8% net interest.
In addition I have a BoS & Halifax reward account thats pays £5 per month each plus one for my wife which equates to £180 plus I have a Nationwide account paying 5% gros on a balance of £2,500 for a year (which will then be switched to anotehr bank with a similar introductory offer).
There are a few hundred pounts to be made each year just for a few minutes of recycling cash between accounts each month - all using money borrowed from credit card companies.