sobrique | Amateur legal advice anyone?

Right, well, I've just got a bit of paper from the warwick camera enforcement unit, saying basically "Busted!". 48 miles an hour in a 40. Temporary restriction, dual carriageway, at 19:30 or so when it was quiet, my speed crept up a bit down the hill. They've since taken down the camera, which is kinda annoying.

However, having read this article about speed restriction signs and this one from the AA it would seem to indicate that there _must_ be speed restriction signs on both sides of the road.

I've sort of reached the conclusion that I might have a get out.
You see, the approach road looks like this:

Now, as I read that article, there _has_ to be a speed restriction sign on both sides of the approach road. Since there wasn't, I'm home free. Or at least, not facing points. Would anyone else care to have a look and check my understanding? I appreciate that for proper legal advice, one needs to seek a proper legal professional, and unless someone says 'naa, that's bollocks' I probably will.