It's becoming quite easy to enjoy discreet conversations in St James's Park these days. There are so many tourists nobody notices the locals, so Sir Douglas Corridor and I thought it would be a good time to compare notes at the Coalition Cafe. However, there were other locals with the same idea, and we were soon interrupted.

Sir Douglas Corridor: Isn't that one of my successors hoving into view?

Sir Nicholas Mandarin: Good afternoon, Douglas. How are you?

Corridor: Put it this way, I thank my lucky stars I'm not at the Treasury any more .

Mandarin: Oh, it's not so bad. I don't have to exercise my brain these days. I just say no to everything.

Corridor: Of course, I'd forgotten. Philip Snowden is alive and well at my old department, and no doubt your political masters are grateful for your support. So tell, me, Nicholas, how is the deficit going. Is it declining?

Mandarin: Er, well, I don't need to tell an old campaigner like you Douglas that these things take time.

Corridor: You mean things get worse before they get better? Quite like the old days.

Mandarin: Alas, rather worse than the old days. Oh, goodness, it's the PM.

Corridor: So it is! (Pause) Good afternoon, prime minister.

David Cameron: Good afternoon, Sir Douglas. What a beautiful spring we are having.

Corridor: Beautiful weather, certainly. (Discreet cough). Tell me, prime minister, do you regularly run around the park wearing dark glasses ? You could be arrested!

Cameron: No, Douglas, things have changed since your day. We all jog, for instance. And we mix with the people.

Mandarin (aside): Or our security men.

Corridor: Were you in the London marathon by any chance, prime minister ?

Cameron: No. But what a good idea for next year! Yes, what a great PR stunt. Where's my note-taker ?

Mandarin: He was one of your cuts. Your private office feel that you must make more use of your iPad.

Cameron : My WHAT?

Mandarin: We in the public sector have to show an example, prime minister. We need to be at the cutting edge.

Corridor (aside): Certainly, no shortage of cutting in this government.

Cameron : Are you winding me up, Nicholas ? Remember, I used to work at the Treasury. I know your tricks.

Corridor: Steady on, you two! Are you not going to acknowledge the presence of the Mayor of London?

Cameron: Eh, what ? Oh God, not Boris. (Pause.) I say, Boris, what are you doing riding a bicycle in a royal park?

Boris Johnson: Didn't you ride a bicycle to work once or twice?

Cameron: Never in the park. It's against the law. And certainly not a Boris Bike.

Corridor: A Boris Bike ? Or a Barclays Bike?

Mandarin: Perhaps they should be called Bob Diamond Bikes.

Corridor: That reminds me, since we have such important people here. Is it true that George Osborne told the Vickers commission on banking to tread softly so that Goldman Sachs and Co would not leave London?

Cameron: Absolute rubbish. They all love London. They'd never want to give up their boxes at Wimbledon. Look at the way they're all piling into number One Hyde Park.

Boris: Quite right. We are the property capital of the world. They all want to live in London.

Corridor: In that case, if it's all empty threats, why go soft on the banks?

Cameron: We mustn't upset the City.

Corridor: Did you not read the other day that Gordon Brown regrets having paid so much attention to the City?

Cameron: Forgive me, Sir Douglas, but do you have to mention that name?

Corridor: I don't have to, but I will. Why aren't you backing him for the International Monetary Fund job?

Cameron: As I told the Today programme, Gordon Brown didn't think we had a debt problem, so how can he recognise debt problems around the world?

Corridor: Well, if I may say so with the utmost respect, I seem to recall that you backed Brown's spending plans.

Cameron: Yes, Douglas. But that was before the crisis.

Corridor: And when the crisis came you opposed all measures to alleviate it.

Cameron: It's the duty of an opposition to oppose.

Corridor: But whatever you think of G Brown, he is generally credited by the rest of the G7 leaders with having been the driving force behind the worldwide measures to save the banks and avoid a 1930s-style depression.

Cameron: That's all very well, but I'm not backing him for the IMF, and that's that!

Corridor: I have to say, prime minister, that this is playground stuff. Whatever the state of personal relations between you and Mr Brown, it's bad form for a prime minister to be so ungracious towards his predecessor. Don't you think it may be time for reconciliation this Eastertide? Even Ian Paisley and Gerry Adams made it up.

Mandarin: Took a few decades, though.

Boris: Hey, wait a minute. This IMF job. I'd quite fancy it if Ken beats me next time round.

Corridor: Why, look, it's the governor!

Mervyn King: What a galère! Good afternoon everybody.

Corridor: Good afternoon to you. We're discussing the IMF job.

King: No, thank you. It's difficult enough running monetary policy in this country.