OK, having tweeked I thought I would come back and share. Being for milkshake rather than cordial meant having to adjust the balance of ingredients quite substantially from the original recipe that judydawn was so kind as to send me. Milk being so sweet means you need less sugar than if mixing with water, but more intense strawberry taste. So without futher ado:
put strawberries, hulled, into the bowl
add their weight in liquid - I used half water, half apple juice (a bottle of Britvic 100% which I happened to have in the cupboard) but I think grape juice might do better. Having said that I think the pectin in the apple juice helped to slightly thicken the syrup so it's a matter of taste. Don't be tempted to use more than half apple juice unless you really want 'apple and strawberry' milkshake LOL
Blitz
cook to 90 degrees at speed 2 - half a kilo of strawberries took about 9 minutes
pass through a sieve into a jelly bag and strain
return liquid to bowl and add sugar - we found 350g to 1000g strawberry liquid a good compromise between what was acceptable to us (no sugar) and what chavvy kids brought up on crusha might accept (not sure there's actually a strawberry in the factory they make crusha syrup at, let alone in the syrup itself).
cook to 90 degrees
pour into sterilised bottles
refrigerate
(Given the low proportion of sugar I added citric acid rather than lemon juice to help extend the 'fridge life'. I forgot to do this before bottling so added 2 level teaspoons to each bottle - about 65cl each - I have no idea if that's enough but I'm not expecting this to last beyond a week given that it's got to go round 60 kids.)
Enjoy
