salt

A few flakes of salt are all you really need, but feel free to dress them up however you like.

"If the ice underneath is rotten - eroded by salt - it'll crumble away under stress and maybe drift somewhere more shallow," says Prof Meijers.

There are also craft sections on making bath salts, a balloon arch and arranging flowers.

Add salt and optional seasoning ingredients like celery leaves and bay leaf and bring to a gentle boil, reduce heat and simmer low until done, about 45 to 50 minutes.

City Hall's Conservatives said the mayor had so far "suffocated" economic ambition in London and that it took the figures in the plans with a "pinch of salt".