Begin by making the jam: place the strawberries and sugar in a pan and bring to the boil then allow to cool.
For the roly poly: in a bowl mix together self-raising flour, caster sugar, suet and lemon juice. Add enough water to form a soft dough then, on a floured surface, roll out on a floured surface into a rectangle shape.
Spread over the jam and roll up tightly. Place onto a large piece of greaseproof paper, then place on a tea towel, tying both ends with string.
Cover the base of a deep large roasting tray with metal spoons - sit a cooling rack on top (or use a rack with legs so the roly poly cannot touch the base of the tray) then sit the roly poly on top. Pour 1 litre of water in the bottom of the tray then place in the oven for 1 hour.
Meanwhile make the custard: whisk the eggs and sugar together in a bowl and in a pan heat the milk, cream and vanilla then bring to the boil. Pour the milk mixture over the egg mixture then return the whole lot to the pan and whisk over a gentle heat until thickened.
To serve: slice the jam roly poly and spoon over the custard.