Turned out to be quite easy to work out which batch it was - it was labelled Marlish Porter . Checked when I made it - August 2015 so 8 years old.I was eyeing up my last bottle of porter I made back in 2017/18 (I'll have to find out which). I made two batches, one used water from a well on a friend's farm, the other from a friend's son's water bottling plant - Marlish water (look at the level of bicarbonate - Bicarb ). I wonder if I can work out which batch it was.
Might give it a test tonight.
Definitely going to test it later.