You can spoil any joke by being cold blooded about it.
I saw it all right when he said it. It was something--something
really very amusing--about the Home Secretary and the Irish
Secretary. At all events, he's evidently the very man to take
with me to Ireland to break the ice for me. He can gain the
confidence of the people there, and make them friendly to me. Eh?
[He seats himself on the office stool, and tilts it back so that
the edge of the standing desk supports his back and prevents his
toppling over].

DOYLE. A nice introduction, by George! Do you suppose the whole
population of Ireland consists of drunken begging letter writers,
or that even if it did, they would accept one another as
references?

BROADBENT. Pooh! nonsense! He's only an Irishman. Besides, you
don't seriously suppose that Haffigan can humbug me, do you?

DOYLE. No: he's too lazy to take the trouble. All he has to do is
to sit there and drink your whisky while you humbug yourself.
However, we needn't argue about Haffigan, for two reasons. First,
with your money in his pocket he will never reach Paddington:
there are too many public houses on the way. Second, he's not an
Irishman at all.

BROADBENT. Not an Irishman! [He is so amazed by the statement
that he straightens himself and brings the stool bolt upright].

DOYLE. Born in Glasgow. Never was in Ireland in his life. I know
all about him.

BROADBENT. But he spoke--he behaved just like an Irishman.

DOYLE. Like an Irishman!! Is it possible that you don't know that
all this top-o-the-morning and broth-of-a-boy and more-power-to-your-elbow
business is as peculiar to England as the Albert Hall concerts of
Irish music are? No Irishman ever talks like that in Ireland, or
ever did, or ever will. But when a thoroughly worthless Irishman
comes to England, and finds the whole place full of romantic duffers
like you, who will let him loaf and drink and sponge and brag as
long as he flatters your sense of moral superiority by playing the
fool and degrading himself and his country, he soon learns the antics
that take you in. He picks them up at the theatre or the music hall.
Haffigan learnt the rudiments from his father, who came from my part
of Ireland. I knew his uncles, Matt and Andy Haffigan of Rosscullen.

BROADBENT [still incredulous]. But his brogue!

DOYLE. His brogue! A fat lot you know about brogues! I've heard
you call a Dublin accent that you could hang your hat on, a
brogue. Heaven h