Normally toilet tissue will completely break apart after being in
water for a short period of time. But these so called 'moist
toilet tissues' now for sale in some supermarkets do not dissolve
at all. Will the sewerage system in north London U.K., deal with these
Strong type moist tissues o.k., or is there likely to be trouble
with blocked pipes, etc?

Next turd passing pushes them out of the way like a battering ram.

You'd be so lucky - or similar lyrics!

I suspect once they hit the main collector line, it's large enough that it would
cause no more problem than all the other non-water soluble stuff that gets
flushed.

I had to auger out the smaller line between the house and the street once. Ended
up being plugged because the SO was using these and they ended up catching on a
burr inside.