Wannabee, just curious - when are you going? We'll be passing through London twice in September and didn't find rates quites as low as you've mentioned (Friday, 17 Sept in particular).
One of our stays is on points, but the overnight on the 17th is with £.
Right now I've booked the Paddington for both stays but for the cash night it's running £109.
This is probably my last year as a Diamond for awhile so being able to receive D recognition will be worth £10-20 premium...