These are very common round here, been used on the old terraced houses
that were built about 1900's.

They were normally used in conjuction with the blue paviers. These
went out of fashion in the 1950's, and as if by magic everybody is
having them back again, or similar ones thou.

If these are the real old rope twists, which I think they are, they
worth a few quid each.

They were manufactured and are of the same hardness as 'blue bricks'.

Repros are on sale at every DIY shed.

The blue paviers were very slippy when algae etc got onto them. I have
just relaid a path with these paviers for a customer, and none are the
same size or thickness.