What good is a nightwatchman?

To the best of my knowledge there are no records of William Shakespeare having had the vaguest interest in cricket, yet his best-known lines, adapted accordingly, seem entirely applicable to one of the game's more dubious customs.

When Liam Plunkett emerged from the Lord's pavilion ahead of Ben Stokes following Gary Ballance's dismissal last Friday evening, with fully seven overs to navigate, admiration for his growing authority at the crease did little to dampen the conviction that caution of this ilk was, well, too damned risky.

The nightwatchman (or, more accurately, the session-watchman) is a profoundly noble creature. In accepting the role he is confronted by no fewer than three tasks: stay put, shield his senior partner from the strike and protect the next man in. That Plunkett succeeded on all three fronts - and, following Matt Prior's exit, outlasted Stokes and registered his maiden Test fifty - is not really the point. Had just one of the short balls he unconvincingly parried dropped within grasping distance of either of India's two short legs, the tactic would have been exposed for all its short-termism and knee-jerkery.

Athletics and cycling have their pace-setters, but nightwatchmanry is the closest any major ballgame comes to baseball's unique reverence for selflessness, for sacrifice as strategy. On the diamond, when team-mates are on base, batters are encouraged to advance them by dint of a sacrifice fly (skying a catch to a deep fielder), sacrifice bunt (push-and-run) or sacrifice squeeze (ditto). Even though this usually means committing hara-kiri, if the score is thus augmented, statistical credit (run batted in) is awarded. Yet only cricket stages games of a length sufficient to render protecting a man from taking the field a defensible gambit. How defensible is another kettle of cod altogether.

To find the most egregious error ever perpetrated in the name of this time-dishonoured ploy we must reel back to Sydney 1933 and, perversely, one of the foremost feats in the annals of nightwatchmanry.

Urn reclaimed, England had just bowled Australia out in the fifth Test of the Bodyline series when Douglas Jardine instructed Harold Larwood to pad up, ready to step up should an early wicket fall. The Nottinghamshire bone rattler, having hitherto flitted between Nos. 9, 10 and 11, couldn't fathom his captain's thought process one whit. He was livid, all the more so when Bill O'Reilly whisked out Herbert Sutcliffe. "I'd bowled my guts out… I was angry. I didn't want to go in. If it was necessary, I was determined to get out."

It was pretty much the only time on that tumultuous tour that Larwood did not have his way. Don Bradman - irony of ironies - should have run him out but missed the target; surviving, somehow, to stumps, Larwood cut loose the next morning, attacking entirely "on spleen".

With the Hill exhorting Harry "Bull" Alexander to "knock the bastard's head off", he unleashed a succession of savage hooks and pulls. He had advanced merrily to 98, oblivious to the scoreboard, when his partner, Maurice Leyland, came down the pitch, informed him he was within touching distance of three figures and suggested he calm down. Concentration broken, he over-thought his next shot: cue hesitation, a checked on-drive and a catch of such extreme dolliness even old Bert Ironmonger, fast approaching 51 and Australia's worst fielder by some distance, couldn't drop it, winning himself a pound from a generous sponsor.

For Larwood, whose score would not be surpassed by an English nightwatchman until Alex Tudor's unbeaten match-winning 99 against New Zealand 66 years later, the legacy was painful. Instead of soothing those aching limbs in a hot bath after Australia had been dismissed, he had been forced to put them through another test of endurance on that unforgiving, brick-hard pitch; come the hosts' second innings, pace conspicuously slower, he collapsed. Jardine ordered him to finish the over but the best he could do was "stand against the crease and swing my arm over".

Bradman, though, was still in, so Jardine insisted the reluctant Larwood remain on the field: "You can't go off until this little bastard's gone. Let him think you can come back for another spell at any time. I want you to stand there and just stare at him." Only when Hedley Verity sent back Bradman did Jardine allow Larwood to "half-limp" off. The sight of him and Bradman vacating the arena together was rich in symbolism. Unsurprisingly, not a word was exchanged.

Larwood took just one wicket the following county summer; never again would he terrorise a Test order - for physical as much as political reasons. "If Jardine's vindictiveness towards Bradman and Australia hadn't overtaken common sense, darkly misting over his rational judgement," warranted Larwood's biographer Duncan Hamilton with good reason, "the rest of [his] career - and perhaps even his life - would have unfolded differently."

As ever, the estimable Charlie Davis has done some sterling work on this, probing and dissecting Tests from 1980 to 1998 with customary surgical precision. Ahead, admittedly, lay not only Jason Gillespie's improbable unconquered 201 against Bangladesh - nearly double the previous best by a Test nightwatchman - but the heroics of No. 11s such as Ashton Agar, Jimmy Anderson and Tino Best, not to mention the unprecedented averages enjoyed by contemporary tailenders. Davis' subversive findings are none the less valid for that.

Calculating that the average contribution by a nightwatchman (in 113 stints) was 15, he compared the 38 instances where one was deployed at the fall of the second wicket with the 36 where not: 33 of the former (nearly 87%) were below the trend line: i.e. the teams did not attain the expected totals. When the nightwatchman was summoned at the fall of the first and third wickets, the respective fruits were 22 sub-par totals out of 34 and 23 out of 35. All told, with six cases "too close to call", 78 out of 107 nightwatchmen (73%) employed at the fall of each of the first three wickets failed to have the desired impact, with the average shortfall 25 team runs per innings.

Davis also addressed the impact of a big partnership on the next, proffering evidence that, contrary to the ill-informed cliché, one wicket does not often bring another. In the years under analysis, the average stand following one worth between 50 and 100 was 36.3; between 100 and 200, it was 41; 300-plus and the next averaged 49.8. In other words, the more substantial the alliance, the bigger its successor was likely to be.

Yes, Moeen Ali and Ballance departed in quick succession last week after adding 98, hence Plunkett's premature entrance, but sending in a nightwatchman still stands in the teeth of statistical probability. Yes, it may well spare a team from further depletion before the end of a session (though it often fails to manage even that), but another downside more than offsets this: the opposition are handed the psychological fillip of a non-specialist to target when play resumes.

Witness the third evening at Trent Bridge in 1965, when England set off in pursuit of 319 to beat South Africa with time aplenty at their disposal, albeit on a pitch only Graeme Pollock and Colin Cowdrey had mastered for long. They were soon one down when Peter Pollock had Bob Barber caught behind and, for the second time in the match, Fred Titmus entered as nightwatchman. He got short shrift, whereupon John Snow loped in. The Sussex poet survived but departed first thing Monday morning. At 10 for 3 the hunt was effectively over; the tourists won by 94 runs with a day unplayed.

The only hint of a home victory came while Peter Parfitt and Jim Parks were biffing 80 in an hour after tea, further fuelling criticism of Mike Smith's promotion of Titmus and Snow. Parks made a feisty 44 before running out of partners: how many more might he have made, and how close might the finish have been, had he not been relegated to No. 9?

Apparently, the decision these days ultimately lies with the batsman due in next, but it is hard to believe that the captain has no input. Another reason to lament that bowlers, being less sensitive to a batsman's insecurities, are so rarely entrusted with leadership.

Which brings us back to the Shakespearian question posed at the start of this column: is the nightwatchman option a procrastinator's charter at best, at worst a coward's get-out? In the immortal words of a more sinister English wordsmith, Francis Urquhart, you may very well think so, but I couldn't possibly comment.