JOY OH joy, my local Tube station has installed automatic gates. Just before this, I overheard a sadistic petty official relishing the prospect of miscreants damaging their limbs while trying to vault over. A heavy punishment, you may think, but not in the league of the summary execution that can befall the chess player incautious enough to snatch a single hot pawn.

Sometimes, of course, it's quite correct to take a pawn, even at the cost of development in the opening, if this damages the opponent's position permanently. Indeed, with the introduction of engines such as (ChessBase's) Fritz and his many friends, pawn-snatching has received ever wider exposure, for these materialistic monsters give great weight to the exact pawn count and often fail, especially if given insufficient "thinking" time, to spot the compensation beyond their search horizons. The blasted things, moreover, are painfully good at defending their ill-gotten gains against us mere mortals: and an overexposure to them may skew our judgement in this matter.

The fact remains, though, that a thoroughly poisoned pawn is thoroughly poisoned, and can be ingested only at at great risk. Take this game from the match, just over a fortnight ago, between Gwent Dragons and Guildford in the second division of the Four Nations' Chess League.

This whole line, jettisoning a bishop so early, looks fairly harmless and King met it head on with the provocative 11 ...Bd6!? If White insists on taking a pawn in the opening, he might try 12 Bxd5!? Nxd5 13 Qxd5 when King intended simply Rb8. Instead Varley decided to "punish" Black's play with the disastrous 12 Qe3+ and 13 Nf4.

When Dan showed me the game, my absolute first instinct in the diagram was 16 ...Ra7, but of course 16 ...Qb6! is infinitely stronger. The main threat is 17 ...Bxh2+ but 17 ...Ne4 is also vicious. Unsurprisingly, if 17 Bxd5 Rae8 18 Qf5 Nxd5 19 Qxd5 Qxf2+! 20 Rxf2 Re1+ 21 Rf1 Rexf1 is mate.

18 ...Bxh2+ was utterly decisive. If 21 f4 Ne3 22 Qd3 Nxf1+ 23 Qxf1 and eg Rxf4 24 Qxf4 Re3+ 25 Kg4 h5+. At the end, White can't even sacrifice his queen to prolong the agony significantly. And all this for one hot pawn!