I've just tried it and it works. I have to go to Bristol at the weekend, so I'd booked a night in a hotel there, coincidentally through hotels.com. When I got the Tesco email I kicked myself, but then remembered there was a free cancellation policy.
I therefore cancelled, exchanged £25 worth of Tesco vouchers for £75 worth of hotels.com vouchers and rebooked at a net cost of £13.35! Added to the value of the vouchers the total room price was still only £38.35, as against a normal price of around £90, so a jolly good deal!
![Very Happy :D](./images/smilies/icon_e_biggrin.gif)
More details here - https://secure.tesco.com/clubcard/boost ... 009591.prd