ID an old SF story?

Someone in my Yahoo book group needs help finding an old SF novel, described thus:

“The book is British, and is one of the earliest examples I know of a genetic-engineering-gone-bad horror story. A scientist in London is experimenting with a species of mushroom, trying to create a super-abundant food source. But the fungus become so voracious that it starts consuming all organic matter that it comes in contact with–which, of course, includes all living things. It escapes the lab and spreads rapidly through the city and out across the countryside, consuming every bit of organic matter in its path. The world soon claps a complete quarantine on the British Isles, but…”

Any ideas?

The Ray Bradbury short story Raise Giant Mushrooms in Your Cellar! ?

I read a book in the 80’s about that called “The Slime” or “The Blob”. Although that started with scientists tipping lab waste into the sewers, and something started growing down there and then coming up through toilets and sinks to devour mankind. The process was completely painless. The only things the slime didn’t eat was cotton (!) and water.

Can’t remember the author though, sorry.

Aha! Apparently it’s The Fungus by Harry Adam Knight.

Walpurgis, I think that’s the one I read. The Slime sounds like the right title. I don’t know where I got The Clone.

Dung Beetle, that’s a Bradbury story I missed. I thought I’d read 'em all!

Thread closed at the request of the OP.