I feel I need to return to this thread and make a top level comment to make sure you see it but after the weekend I have had I need to update and rescind my recommendation for the Meroca tubes.

I guess I was just really lucky with the first two that I used and gave me no issues for quite a while but at the weekend I got my first puncture, fine, these things happen. The following 2 brand new tubes I used though that I had as spares would not hold air as they leaked through the valves and consequently I had to cut my ride short and do a lot of walking.

So I won’t be using that shit again, my luck must be out now and I cannot in good conscience recommend those tubes!