Five years ago, the first domestic Twenty20 match at Lord’s attracted 30,000 spectators. The two matches at Lord’s played so far this season have attracted about half that number – not each, but together. All the counties are seeing smaller crowds this year than last, and last year’s were lower than the year before. TV ratings for the IPL this year were down about 15% on last year.

The novelty value of Twenty20 seems to be wearing off. It has undoubtedly brought new people into watching cricket, whether live or on TV, but long-term success depends on whether these new cricket spectators carry on watching.

If their continued loyalty is dependent on the games being exciting, though, the prospect is fairly bleak, because relatively few Twenty20 games are particularly exciting. Only about 30% of games in the IPL have come down to the last over, a figure similar to the English domestic competition. In international Twenty20, fewer than one game in four goes to the wire. At least half the games are pretty much done and dusted by the end of the second innings powerplay, the remaining hour of the match merely giving concrete form to the inevitable.

Not that these figures are bad - in cricket terms. Longer games are even less likely to change their obvious trajectory in the last hour of play. But it compares very unfavourably with other mass-appeal sports.

In huge numbers of soccer games, the result is still uncertain with five minutes to go: a single goal would still be enough to equalise or one side to take a late lead. Hoping to get five runs in the bottom of the ninth in baseball may require huge optimism, but making up a one or two-run difference remains within most teams’ capacity - it only takes one big hit.. With their higher scores, oval ball codes of football tend to be more or less decided rather earlier – once a team needs to score more than once and at least every five minutes, they are very likely to lose – but the tension usually lasts well past the two-thirds point.

Twenty20 moves considerably faster than the longer forms of cricket, but by comparison with other sports it is like watching people racing through treacle.

Longer forms make up for inevitability by offering a stage for individuals to shine. Within the context of a virtually-decided match, there are often subsidiary dramas to sustain interest. Bowlers can get useful hauls and batsmen can play innings long enough to be memorable. Twenty-wicket cricket, whether four-day or five-day, has the further advantage that while it may be obvious that one side cannot win, the possibility that they will not lose remains open right until the end.

Twenty20, though, depends almost entirely on the result for drama. In four overs, a bowler is doing well to take even two wickets, and it takes something spectacular for an individual batsman to stand out. There is much less to talk about with your mates on the way home.

I am not trying to knock Twenty20. I enjoy Twenty20 a great deal. It doesn’t bother me that it does not in practice live up to the ambitious marketing of thrills and spills all the way; I am wholly accustomed to watching matches where not much happens, so one close game in three is quite OK in my book. What is far more dubious is whether the casual fans who have been sufficiently attracted by the new format to give boring old cricket a try will persist with it once they’ve rumbled that underneath the glitz, flashing lights and dancing girls, the central attraction is still cricket.