You need a bucket and spade and a landscape expert, says architect John Pawson
"You have to pick your beach, as the sand is very important. According to my landscape expert, it should be sand with a high clay content which results in less slump. I think that means falling down. Alluvial sand is good - so build your sandcastle on a beach near the mouth of a river or stream. When I was a child, we had a holiday house in Filey where the sands seemed to be perfect for sandcastles. When I was asked, along with several other architects, to build a sandcastle for Vogue, I was allowed two tools. I asked for a proper spade and wheelbarrow, and a spirit level - but that was a joke. I built a huge pyramid and then dug this channel all the way inland, so, when the tide came in, the water rushed up it. I was trying to make it look like the Taj Mahal in a flood! As far as equipment goes, you only really need a bucket and spade.

I'm not a great one for flags and accessories, but I do like repetition. My father liked steps, which are repetitive (That's me as a child in the image, with one of Dad's castles). He was in the rag trade, but he would have liked to have been an architect. My kids, Caius and Benedict, are 11 and 7, and building sandcastles is the one thing they can do together without fighting - it's a great leveller. Fathers should try not to be obsessed. Building sandcastles always starts out for the children but you often see the father taking over and getting irritated with the children, who get pissed off and walk away"