Some dodgy reasoning on that site though
The highlighted paragraph says that there are two dedicated members of staff working on each of the vehicles every week, completing the vans in a six month period. The conclusion to be drawn is that there are 26* vans.
Nothing there says that they only have 2 members of staff in total – just that 2 members of staff work on each van. Hence the 26 van conclusion is flawed. Lots more examples of similar levels of reasoning (eg the legal evidence thing – they don’t use the evidence from the vans to prosecute, simply to advance the legal process in other ways, hence the evidence laws are different).
I have no evidence whether or not they have working detector vans, but it would surprise me if they didn’t use such technology, given it’s very straightforward and could be very useful in determining whether somebody really does have a TV – I note a distinct lack of evidence from those who use a TV but have no licence on whether a detector van was involved.
An amusing anecdote – many years ago I was involved with doing radio trials in Scotland which involved driving round in a white Tranny with a great big retracting antenna in the middle of the roof. One morning after staying the night at a pub in the middle of nowhere on Skye the landlord asked if we were a TV detector van, and commented that lots of locals were busy buying licenses 🙂