From the other green bench ,the man generally raises his elbows and feet and heaves a profound sigh after all that is over. Morning ritual exercise can be boring. Now there is another man who is making nostril noises.
Poet Betjeman , it seems, did not like Slough. He wanted it to be bombed. In WW2, it turned out it was indeed to be bombed. He wanted the last laugh on a town ,so utterly soulless. A town which celebrated bodies.
The poet had the last laugh, in the sense he would be the one laughing last, when he would no more last . After a last laugh the poet would be posthumously happy. He might have made hay while the sun shone but all was cold now. He might be waiting to collect his last laugh that was his bonus. He might have been one up, that is literally at his last croak.