Originally Posted by paulieuk

Try using the link on Raffles' Head For Points blog, which includes a direct link specifically to Sofitel's secret hotel booking page and you then just put in your dates to see if availability exists.

On his blog page, the specific direct link is where it says "This hotel is the Sofitel at Heathrow" on the start of paragraph 4.

I've used it twice now to secure the Sofitel at the magic rate.

At least then you know if there's "secret" availability or not. And if not, keep trying back nearer your dates....