I took a day off work on the Friday before Hanwell Carnival to help set up the largest single-day carnival in London. It was a lovely, sunny morning, and I was looking forward to dialling down my brain activity while doing some fun, physical GoodGymming — think setting up gazebos!

"How good are you with maths?" — Sue, the Carnival volunteer.

Wait, what? So there was no escape from number crunching today. At least we were going to do it in real life. Sue and I, later joined by other volunteers, had a task to mark out all the pitches for the stalls that would be set up later. And the stallholders were bringing their own gazebos to assemble themselves! No gazebos, no shade... Well, I was up for a new experience.

Sue and I grabbed tape measures (which were abundant) and metal pegs (not so abundant) and started drafting the imaginary layout of the stalls based on Sue's map. We had to make sure that the rectangles we marked out — the first one was a whopping 60 by 30 feet — had proper right angles. Luckily, we weren't tested on our mental arithmetic by having to apply Pythagoras' theorem ourselves, as the measurements for the sides and diagonals had already been worked out. Phew!

Having marked all the rectangle corners with pegs, we then had to use orange string to outline the sides. Here's where the complication began. If you've been to a few GoodGym sessions involving event setup — with twine, bunting and other things that love getting tangled — you'll know exactly what that means. The string was, of course, tangled. Our predecessors must have been in a hurry and left the twine to joyously develop knots and loops designed to test our patience.

With two brains and four hands, Sue and I managed to unravel the string, which, just like Ariadne's thread, led us to our goal (no Minotaurs involved): a perfect rectangle ready to be marked with white spray paint. I had the honour of driving the machine normally used to mark football pitches. So far, I've managed to avoid getting involved in discussions about the World Cup, but apparently I couldn't escape football altogether!

As Sue and I marked out the internal sections of our giant rectangle, volunteer Mina arrived to help us with the next stage of the task.

Who would have thought that Greek geometry and Greek mythology would be the most useful subjects for marking out carnival stall pitches?