One of the common law's best known creations is the man on the Clapham Omnibus.
As is fitting, he took his seat almost unnoticed: first mentioned in a law report by Collins MR in McQuire v Western Morning News Company  2 KB 100 at 109. The then Master of the Rolls wished not to praise him, but to keep him quiet. The Court was determining whether a theatre critic's review had been "fair comment" and was anxious to hold that "fair", in that context,
"does not mean that which the ordinary reasonable man, "the man on the Clapham omnibus," as Lord Bowen phrased it, the juryman common or special, would think a correct appreciation of the work."
The reference to Lord Bowen's use is not clear from the judgment but he is said to have used the phrase as an advocate in the famous Titchborne Claimant case of the 1870's. If so, then perhaps Walter Bagehot had that in mind when he wrote in The English Constitution in 1873,
"Public opinion ... is the opinion of the bald-headed man at the back of the omnibus"
Clapham would represent an unremarkable and ordinary area of London. Our man himself seems to be ordinary and unremarkable, and yet he has endured.
Over the nearly 150 years since his creation, the Courts have adopted an increasingly affectionate, even reverential tone when considering the man on the Clapham Omnibus.
He is a perfect symbol for the common law - constant yet adaptable. A figure of solidity and yet, like justice itself, tantalisingly indefinable. Sir Percy Winfield rudely called him a "sloppy thinker" but accepted that he was someone who knew how to put the phrase "justice as between man and man" to practical use, even if he could not explain it.
So totemic of ordinary British reasonableness has he become that Lord Reed was able to describe him and what he represents in some detail in Healthcare at Home Limited v. The Common Services Agency  UKSC 49:
"1. The Clapham omnibus has many passengers. The most venerable is the reasonable man, who was born during the reign of Victoria but remains in vigorous health. Amongst the other passengers are the right-thinking member of society, familiar from the law of defamation, the officious bystander, the reasonable parent, the reasonable landlord, and the fair-minded and informed observer, all of whom have had season tickets for many years.
2. The horse-drawn bus between Knightsbridge and Clapham, which Lord Bowen is thought to have had in mind, was real enough. But its most famous passenger, and the others I have mentioned, are legal fictions. They belong to an intellectual tradition of defining a legal standard by reference to a hypothetical person, which stretches back to the creation by Roman jurists of the figure of the bonus paterfamilias...
3. ..... The behaviour of the reasonable man is not established by the evidence of witnesses, but by the application of a legal standard by the court. The court may require to be informed by evidence of circumstances which bear on its application of the standard of the reasonable man in any particular case; but it is then for the court to determine the outcome, in those circumstances, of applying that impersonal standard.
4. In recent times, some additional passengers from the European Union have boarded the Clapham omnibus. This appeal is concerned with one of them: the reasonably well-informed and normally diligent tenderer."
The bald man at the back of the omnibus has changed with time. Certainly, he no longer rides on a horse-drawn bus. But is he still bald? Is he in fact male, or would that prevent him being representative of both, indeed all, genders? I imagine that as conceived in the Victorian era, he was white and Christian, but now he must represent all races, and people of all faiths and none.
These changes make him more difficult to conjure in the imagination - the greater the range of people he represents, the less specific he becomes.
Nevertheless, we still need him. We need him more than ever.
He is impartial: he is a disinterested observer.
He is rational: he does not allow prejudice, blind faith or distrust to cloud his judgment.
He is well-informed: not an "expert" but an inquisitive generalist who gathers, assimilates and weighs the available information before making a judgment.
He is reasonable: he takes into account differing views and perspectives. He allows for uncertainty. He balances evidence and argument.
It may be more difficult to pin down this fictional figure to a specific gender or race, but I hold on to the idea that he is seated at the back of the bus. It suggests a quiet, observant individual. He sits alone and sees the other passengers in front of him in all their variety. He is anxious to become well-informed and is slow to judge. He is restrained, unlike his interfering cousin, the officious bystander.
Although he has lived for nearly a century and a half, in my mind's eye he remains middle-aged. He has experienced both the joys and travails of life but is not cynical nor yet worn down.
However you imagine him, you know that he has a deep well of common sense: a sense of practical justice, so-called because it is common to all rational, fair-minded people, whatever their gender, race, health, talents, wealth or political affiliations, not the preserve of a particular type or group.
The man at the back of the bus has endured. He has survived an onslaught of statutes and regulations. He has shaken the hand of human rights but not moved from his seat. Whilst others shout to be heard, he has maintained a quiet dignity.
Long live the reasonable man. Long live the man on the Clapham omnibus.