‘These tests were great for recruiting a certain kind of thinker’

Icame across GCHQ via a recruitment notice in The Daily Telegraph. I was at university studying maths, and found it intriguing. Back in the Eighties, nobody knew much about what GCHQ did. When I turned up for the entrance exam I was taken to a room and given a set of puzzles. I thought if that was the sort of thing you had to do to get into the organisation, I knew I would enjoy working there.

The entrance tests have changed quite a lot since my time. The tests then were great at recruiting a certain kind of logic and maths thinker, but now we’re interested in a more diverse range of thinking.

I led the team that produced the puzzle elements for the first GCHQ Puzzle Book in 2016, and now for the second book, too. The first book was a surprise bestseller and we raised more than £330,000 for the charity Heads Together. We were amazed by how successful it was.

At GCHQ, we’re always sharing and doing puzzles for fun – there’s a Christmas quiz and a treasure hunt.

Our puzzles are different to normal crosswords. Ours have deliberate mistakes in them and there can be more than one answer. The idea is to replicate what it’s like in the real world. You need a mindset that can cope with the grey, because you can never trust that information is 100 per cent correct.

While putting the second book together, we found a set of entrance tests at the bottom of a filing cabinet, including those reproduced here. The answers were nowhere to be found, so we have had to recreate them from the questions. Some questions have more than one possible solution, so if anyone is able to come up with better answers than the ones we’ve provided, we’d be very keen to know!