Boil the juice down until only 3 cups of it remain. Add the sugar. Stir until dissolved. Boil for 5 minutes, skimming if necessary. Pour into sterilized bottles at once and seal or cork.
Conkers are horse chestnuts.
We would take them home and string them together on very strong string. Sometimes we would coat them in varnish to make them hard. Then, armed with a string of conkers we would go off looking off for other conkers to conquer - pun absolutely intended. The other person would then aim his or her conker at yours in an attempt to split it and break it off the string. I liked that game.