lock 2 lock

"The scheme is simplicity itself. By attaching a L2L sticker to your
bike, motorcyclists can help to drastically reduce motorcycle theft.
The L2L sticker displayed on a motorcycle authorises another
Lock-2-Lock member to lock his or her bike security chain to that
particular bike's security chain. Only the locks are locked together,
therefore any of the bikes can be removed from the "chain" of bikes
when the owner desires."

Good idea or a waste of time and effort?

I'd guess "The latter".

Amateur thieves won't usually bother with a bike with a decent chain &
lock on it, and pros can defeat almost any lock/chain combination with a
mix of X, Y and Z [1]. There's even the point that a chain securely
chained round *your* bike so there's no slack is trickier to defeat,
whereas by, say, lobbing it round a U-lock or similar on someone else's
bike, you're then giving the potential thief slack and/or a fulcrum to
work with. As you doubtless know, if there's slack or a fulcrum to work
with it's *much* easier to defeat a lock or chain.

Plus of course you have to rely on the other biker being bright enough
to get his chain off without clonking your bike, which doesn't strike me
as a given.

[1] I'm not listing them coz I'm not giving any dumb scrotes a free
lesson, but I'm sure you can guess what the 3 things are. Email me if
you're in any doubt

This scheme is at least ten years old.

I'd not heard of it before, but having read the blurb, you're right.

The email got sent to us at work, as they're having a new promotion of
it between 21/7 and 4/8 this year, in conjunction with the City of
London CDRP (Crime & Disorder Reduction Partnership)

IIRC, one of the bike mags, or it might have been MCN, started
off the idea and gave away loads of "lock2lock friendly" stickers
to put onto your bike.

Again, I didn't know that.

It's a great idea, and would certainly make it harder to lift a
bike into a van, but I don't get why you'd want to pay =A310 for
a couple of stickers and some discounts?

fair comment, but I guess there's some admin overhead. I guess it
ought to be funded by the police, as they're failing in their duty of
care if your bike gets nicked.

Lol, that would be a great point to make at an open day!