Brad Haddin, the vice-captain who has led Australia onto the Adelaide Oval when Clarke has been absent, is the logical and the best replacement. He is already a leader. His appointment as 45th Test captain would be less momentous than his standing as Australia's 29th Test wicketkeeper. We have had 32 keepers in all (Graham Manou, Tim Paine and Matthew Wade have each had a turn in Haddin's time), and the keeping job has always had more stability about it than the captaincy. Since 2008, this has been the Haddin era, just as before him there were the Gilchrist, Healy and Marsh eras, back to the era of Prince of Wicketkeepers, John McCarthy Blackham.

Blackham was, however, one of only three men to hold both jobs. The other two (Barry Jarman, one Test match in 1968 and Adam Gilchrist, six Test matches between 2000 and 2004) were fill-in captains. Jarman, known for his attacking approach to the game, led Australia to a stodgy draw to save the Ashes, apparently on the orders of injured captain Bill Lawry. Gilchrist deputised for Steve Waugh twice and Ricky Ponting four times, and although successful, winning four matches including the historic 2004 series in India, he was reluctant to lead and relieved to hand back the reins.

Blackham, from 1891 to 1894, was the only Australian wicketkeeper to be first-choice Test captain. (He had previously led Australia for one Test match in 1884-85, but as a stand-in when other players, including captain Billy Murdoch, were banned over a financial dispute.) Blackham, the fulcrum of Australian Test cricket for its first two decades, was unhappily nervous in the captaincy. During one Test match in England, he rode in a cab around the ground for hours rather than watch his teammates chase a total. In Sydney in 1894-95, Australia scored 586 in the first innings but England, following on, set them 177 to win. On the penultimate evening, Australia were 2/113. But then it rained. At the Baden Baden Hotel in Coogee that night, all-rounder George Giffen wrote, 'the match seemed as good as won. All of us thought so that night save Blackham, who feared rain. I know I turned in to rest with an easy mind on the subject. When I awoke next morning and found the glorious sun streaming into my room, I was in ecstasy. But the first man I met outside was Blackham, with a face as long as a coffee-pot. The explanation of his looks came with the remark, 'It has been pouring half the night, George."

The foremost wicketkeeper-captain but also the miserablest, Blackham had been up all night. In England's hotel, so had spinner Bobby Peel, who drank to dull the pain from five extracted teeth. When he was still inebriated, not to mention anaesthetised, on arrival at the SCG, his captain Andrew Stoddart put him under a cold shower. Peel said, 'Give me the ball, Mr Stoddart, and I'll have the buggers out before lunch.' Peel took five of the eight Australian wickets to fall, England won by ten runs, Blackham mooned about the pavilion muttering 'Cruel luck, cruel luck', and, having chipped a finger earlier in the match, never played for Australia again.

So the portents are not, as they say, good. Haddin has been the perfect vice-captain for Clarke since 2013, being widely respected and unambitious for the top job. So unambitious, in fact, that he is probably the first in line urging the medical staff to piece Clarke together. And Haddin has his own challenges. He injured his right shoulder just a month ago. His wicketkeeping remains exemplary, but at 37 he would know how quickly it can go and would not be taking one session for granted. His batting average since his wonderful 2013-14 Ashes series has gone south, as if it had to revert eventually. There is no law of averages, but the perception of one in a player's mind is much more corrosive, being real.

If Haddin were excused, what then? Steve Smith is playing so well that to give him the captaincy ahead of his time could, as Devo sang, crush that dove with a ton o' love. Also, to give Smith the job might shake the ideal of continuity: this remains Clarke's team, not yet his successor's, if Smith is indeed that man. Shane Watson's position should take up more time at the selection table than the board table. Drafting in an outsider such as George Bailey would be putting an English cart ahead of the Australian horse. If Clarke is only to miss one game and Haddin really doesn't want the burden, my suggestion would be radically mild: give the captaincy to Ryan Harris. He is mature, articulate and respected by all. Despite his being an opening bowler - Ray Lindwall, who led for one Test match in India in 1956-57, is the only precedent - these days, the support staff led by Darren Lehmann and the leadership group within the team would see Harris through. Clarke can still pick the batting order and Shane Warne can semaphore the bowling changes and funky fields. And who knows? Geoff Lawson was a terrific captain late in his career. So was Courtney Walsh. Harris would certainly be a figure his team could rally around, without unsettling the natural order of things, and cricket followers would do the same, seeing it as a reward for service. No doubt it won't happen, but there are, and have been, worse reasons for giving a man this highest honour.