How strictly are the new carryon luggage sizes being enforced?

On the BAA site, they are indicating the new regulated size of carryon luggage for travel to the UK, roughly 14 x 12 x 6 inches. I have a camera bag that’s about 10 x 8 x 8. Now, there’s no way I’m letting my camera out of my sight and I’ll carry it on by itself if I have to. But can anyone who’s travelled to the UK by air recently tell me if they’re very strictly enforcing that size, or is that going to be close enough not to be bothered with?

I recently travelled from Stockholm via Heathrow to the US. They had a luggage sizer at Heathrow, and made me show them that my carryon bag could fit into it. They are strictly enforcing it in at least some cases- they didn’t do that to everyone, but they are doing it. I would carry the camera on without the camera bag, or not take that particular camera with me unless absolutely necessary, if I were you.