There was a joke shop in Tooting which was the ideal destination for anyone who was an aspiring Dennis the Menace or Beryl the Peril.

Because everyone likes to scare their grandparents with a pretend severed finger or plastic tarantula casually placed next to their February 1965 edition of the Reader’s Digest and glass of Complan.  Or create a smell which really couldn’t be blamed on the dog (whether you had a dog or not) and that, after you’d created the accompanying noise with a whoopee cushion placed under an aged relative.

For me, the best thing in the shop was invisible ink.

Watching Dangerman (like Danger Mouse only with less cheese) in the sixties, I wanted to be John Drake – or anyone on TV who was a spy.

I would leave notes, written in invisible ink, for the cleaners of our Balham flats (they were my nemesis and I knew, while on their fag break, they’d automatically reveal my messages).

Having run out of the shop-bought invisible ink, I’d create my own, using lemon juice.  My mother would often wonder why her bottles of Jif ran out so quickly.

I left messages for my mum, but these always backfired because a. her reading skills weren’t very good and b. her lighter was modelled on a make that Red Adair wouldn’t have recommended.  So, rather than knowing I was going to be late for my tea, my mother was busy ringing the Fire Brigade.  To be fair, she did like a man in uniform.