I shed a quiet tear now, for the secret is out at last.
We called it "Diddy Fishing" back then -- my pal, Chris Purser and me -- as we fished Little Boyer's Pit at West Drayton / Harmondsworth (the latter place our home"), as kids in the mid-1960s, for tench. But all that waiting after the obligatory textbook swim-raking and plastering with breadcrumb and stale-loaf mash...
So, it was dead reed stem (heavy gear) or a strand of sun-dried long summer-grass (the usual), the world's smallest porcupine quill floats (1.5. to 3 inches, I still have them), the tiniest hooks (18s, probably, back then), a fragment of a worm found beneath a lifted bankside tussock, then into the margins with the stuff.
Diddy perch and diddy roach (and, occasionally twice, a real monster - a half-pounder that usually monstered us - and once a half pound tench that I managed to land -- Chris wouldn't speak to me for ages afterwards, even though, at the time, his PB tench was 4 pounds (massive) to my three.
Ah, Joy in the Morning! (afternoons actually, in the heat of a July afternoon before the serious stuff stuff of the evening). And what fun! We quite forgot all the swanky gear we'd plagued our folks to buy for us to fish for tench.
Keep this quiet, fellas, or the trade will be onto it.
"We gave you carp, then pike, then barbel, and now... behold!
Back to where some of you (all of you, once upon a time) started."
Be afraid, very afraid.