The payoff works, but up to then, zero laughs. So no, not even close to being "the best UK comedy sketch of the 1970s".
I couldn't help thinking the whole time, "why doesn't he just tear the note?" I assume the laws in the UK are similar to those in the US regarding damaged bills - if a torn bill is at least 51% of the original, it's still considered legal tender. Knowing that you could have just tear off the majority of the note, and be on your way, makes the whole skit moot, and therefore not funny.