Fortunately, we were fully aware of Tom's allergy and three weeks earlier we had been trained in the use of the Epi-pen. This pre-sealed hypodermic device contains a measured dose of adrenaline that can be injected into a child suffering from anaphylactic shock brought on by such an allergy.
First we called the ambulance. At the same time a member of staff collected the Epi-pen, which was prescribed by Tom's doctor, from the medicine cupboard.
Tom was tearful but coping. The Epi-pen is pushed hard on to the top part of the leg; when you hear a click, you hold for the count of 10. The child doesn't even have to undress - you can do it, as we did, through the fabric of trousers.
The needle cannot go deep enough to hit an artery or vein and the amount of adrenaline is no more than goes into your body when you are very frightened.
The ambulance arrived 25 minutes later but thanks to the Epi-pen Tom only needed to be taken to be checked at hospital.
As long as you have staff willing to be trained by a local health specialist in the use of the Epi-pen, it is a simple and safe method of dealing with a life-threatening emergency.
Penny Allsworth is acting head and Frieda Baxter a nursery nurse and first-aider at Colnbrook School, a primary for children with moderate learning difficulties in Watford, Hertfordshire.