The legal expression of 'the man on the Clapham Omnibus' was first introduced in 1753 in the case of R v Murphy by Philip Dunwell, in relation to a Northcote Road Chandler, Reginald Toff. Toff was due to give testimony implementing the case, however he failed to attend at the allocated time, as a result the court sent earnest law clerks to Chancery Lane. As a Clapham omnibus passed by, Dunwell shouted "That's our man, the man on the Clapham omnibus! "(1).
The term was later coined by Bowen L. J to refer to 'the reasonable/ ordinary man' on the street whilst concluding the case of McQuire v Western Morning News  2KB 100 and confronting the jury with the question "We must ask ourselves what the man on the Clapham omnibus would think. " (2). This was then later used to asses by common law the standard of care of that of the average man. This standard of care was acknowledged by Greer LJ in Hall v. Brooklands Auto-Racing Club (1933) 1 KB 205 when discussing the case Greer LJ stated "it must be judged by what any reasonable member of the public must have intended should be the term of the contract"(3).
The plaintiff had a duty to see the course was as safe as "reasonable care and skill could make it "(4) however there was an appeal from McCardie J, which was then allowed as it was seen that no reasonable person can guard from every possible danger. The man on the Clapham Omnibus cannot be compared to a professional person as he does not uphold any professional knowledge or skills, the term professional can connote anyone who gives specialist advice or service.
This can range from a solicitor to an IT consultant. Therefore, unlike the man on the Clapham omnibus a professional is under a legal duty to exercise "services with reasonable care and skill" (5). However a person is only required to show the skill of a person in the same field. In Wells v Cooper  the claimant was injured by the defendants door handle whilst making a delivery. The handle was fixed on by the defendant a few months earlier. The defendant had some experience as an amateur carpenter.
Jenkins LJ stated that "it was a trifling domestic replacement well within the competence of accustomed to doing small carpentering jobs"(6) and therefore his skills would not be comparable with one of a professional carpenter and held that the defendant was not liable for breach of duty. In majority of cases the professionals would have signed a contract with the claimant to provide the professional knowledge or skill they promote and within those contractual terms there has to be a breach or liability.
For that liability to be established the claimant must be able to prove that the defendant owed a duty of care and that the duty was breached causing a loss which would have been reasonably foreseeable or the standard of care that expected of him fell below that of the professional in the same field. This is known as the "Bolam test". The Bolem Test applies to all professionals and measures whether one has provided his standard of care whilst treating a client/patient.
This standard of care was laid down in the case of Bolam v Friern Hospital Management Committee  were it was alleged that a doctor had been negligent when failing to give a relaxation drug before the treatment on the fractured pelvis, as a result the plaintiff suffered a fractured jaw. It was held that the defendant was not liable. Mcnair J whilst addressing the jury stated that "… where you get a situation which involves the use of some special skill or competence, then the test as to whether there has been negligence or not is not the test of the man on the top of a Clapham omnibus, because he has not got this special skill…
if a surgeon fails to measure up to that standard in any respect or he has been negligent and should be so adjudged" (7). The case suggests that even if the professional chooses the least popular or obvious choice, it does not necessarily amount to professional negligence if someone in the same field can support or justify it. Since the Bolem case there has only been 1 reported case that the courts took the view that established practise is unsatisfactory and found negligence.
That is the case of Bolitho v City and Hackney Health Authority  3 WLR 1151 were a 2 yr old with croup died due to a sudden respiratory crises. A nurse urgently called for a doctor, the defendant, who then negligently failed to attend, her substitute's pager had run out of batteries and was unable to be reached. Had the doctor attended and carried out the required procedures (intubated him) then the child would have lived, but not all the doctors would have intubated him and the defendant said she would not have done so.
Dr Horne did breach her duty of care after being notified of Bolitho's condition on numerous occasions. As negligence was established, causation had to be decided, but the trial judge held that, judging by the 'on the application of Bolam test (perhaps it's high tide mark) the court had no choice but to agree with the Defendant Experts and apply the principle that where the medical profession itself cannot agree as long as the doctor was acting in line with a responsible body of medical opinion he cannot be held liable' (8). Therefore causation could not been proven.