As his successor, David Laws, explained this morning:
'When I arrived at my desk on the very first day as Chief Secretary,
I found a letter from the previous chief secretary to give me some
advice, I assumed, on how I conduct myself over the months ahead.
when I opened it, it was a one-sentence letter which simply said "Dear
Chief Secretary, I'm afraid to tell you there's no money left", which
was honest but slightly less helpful advice than I had been expecting.'
Byrne is saying that his letter was " a joke, from one Chief Secretary to another".
It was certainly rather shorter than the memo he infamously wrote for his civil servants about how to make his coffee.