Speed limit change at the end of roadworks?

[mjb1]

Coming out of some road works the other day to be greeted by a camera van. Roadworks were 30 limit (single carriageway with a normal limit of 50). The next road sign was a 50 repeater, but as far as I can recall there are no signs anywhere saying it's the end of the road works/end of the temporary limit. Does that mean it's 30 limit up to the 50 repeater? Should have stuck to 30, but I appeared to be clear of any road works activity, so started to accelerate along with the the stream of the traffic I was in. Not sure how fast I was going when, probably about 40. I'm guessing I was still in the 30 section and that's why the camera van was targetting there, must be like shooting fish in a barrel for them.