Taking those berry pics this morning gave me a craving for some brambleberry cordial. Luckily there was still about 4 kg of berries in the freezer from last season, so I whipped out a couple and made cordial. I modified a recipe I found on the ABC (Australia) website.
For each kg of berries add 1 litre of water, bring to the boil and simmer 15 mins. Strain through muslin (I hang mine to get every last drop of berry juice!). For every cup of berry liquid add 1 cup of sugar (I use a bit less), stir to dissolve, then bring to the boil for 3 minutes. Turn off the heat then add 85ml of white vinegar for every kg of berries you used (in my case it was 170ml for 2kg of berries). Pour into sterilised bottles and seal. I got about 4l of cordial. Serve a splash of cordial with water or soda water. You don't need much and it lasts for ages.