What does the phrase "in my puff" mean?

Solution 1:

I never heard this expression before, and it doesn't seem to have much currency today (but see comments below - it's still known to some in the Midlands / north of Britain).

It seems pretty clear to me the meaning is in my life, and I'd guess puff in this sense means something like breath (i.e. - for all the time I've been alive and breathing.

I would not advise using the expression, since many people (not just OP!) will probably not understand it.

Solution 2:

The phrase "in my puff" means "in my life", as in "I've never heard such a load of rubbish in all my puff". This expression is still widely used in Scotland, especially around the West Coast, and in Glasgow in particular. It was a favoured expression of my father who was still using it up until he died, aged 70, in 2008 !

Solution 3:

Eric Partridge, Dictionary of Slang and Unconventional English, fifth edition (1961) has this relevant entry for puff:

puff. ... 4. Life ; existence : tailors' [slang] (low ) gen[eral use] : from ca. 1880. As in never in one's puff, never, and as in 'Pomes' Marshall, 'He's the winner right enough! It's the one sole snip of a lifetime—simply the cop of one's puff.'

So Partridge confirms that Wodehouse was using puff as a slang equivalent of "life" or "existence." This may be the first time I've seen a slang term categorized as tailors', and I regret that Partridge doesn't pursue the question of how it arose in the context of that profession.