So I poked it into our piece of beef and put that into the pre-heated oven, but for boeuf en croute you hardly pre-cook the meat at all, so I had my eye on the thermometer from the off.
To my amazement, after a few minutes, I saw the clear front of the instrument, which I had taken to be glass, balloon up and start to blister. Clearly it was plastic, not glass, and completely unfit for purpose. I whipped it out pronto, in case it started to give off toxic fumes and ruin my Aberdeen Angus!
Sadly, I didn't think to photograph it before setting out for the store, which is why I used my phone to photograph it propped on the bonnet of the car.
Tesco refunded my 74p, and promised to take the rest of the stock off their shelves, but you have to wonder how much product testing they do before releasing stuff like this on an unsuspecting public!