Lovely part of Wales that Graz, been many of time in Pembroke, you will love it if you haven't been there before, you should pay a visit along the Gower coast line, my old stomping ground :thumb:
Check around the lock seal ie bung, put I bit of water Round the seal to see if bubbles appear there as I had a similar issue once where the bung needed replacing for a tighter one.
Also try putting a small weight on the lid to stop it bulging so the ferm has to come out of the trap.
If...
I brewed a Brains SA clone this weekend gone sweet wort was lovely extra helping's of Crystal malt.
However the fermenting took a whole to start had correct temperature etc just didn't go...
So I kicked started it with a half a sachet of strong cider yeast and a teaspoon of bread yeast...
I re fired a friends 14.7 ABV Cider the other day as I thought I am not drinking that drain cleaner lol.
So I put his 2L into 3L of good pure apple juice and added some good high pro cider yeast and it's going fantastic in the 2nd hand demijohn I bought the same day for ã3.50 so to top it...