Barristers tend to be grouped in chambers. “Chambers” is an old word for “rooms” and originally each barrister rented a room in one of the four Inns of Court which are located on the border between the old City of London, founded by the Romans, and the City of Westminster which became the centre of law and government after the Norman Conquest. The rooms in a building, or on the floor of a building, within one of the Inns constituted a “set of chambers” with the individual barristers being tenants of a senior barrister who was “head of chambers”. This system still operates but in the 21st Century, with the widespread use of computers and email, the physical building is of lesser importance. For regulatory reasons every barrister has to have an official physical address at which they can be contacted (which can now be located anywhere in England or Wales) but the chambers building tends to be used more as the place where chambers clerks are based rather than as a barrister’s habitual place of work, and many barristers whose practices have developed in a specialised field of civil law, and who are quite mobile, practise in tribunals, and advise on matters, over a wide area of England and Wales, not only, or even mainly, where their chambers happens to be physically located. Chambers is a place where barristers may have a conference with clients but in many cases somewhere else may be more convenient – such as on site in the case of a land dispute. But whilst the building itself may be of lesser importance the association of barristers together as a chambers is still important as a means by which one barrister can cover for another in the event of unavailability, and when the word chambers is used nowadays it usually refers to the group of barristers with their supporting clerks rather than literally to the chambers' building.
If the barrister who a client usually uses is unavailable, the chambers' clerk may – because they have access to the diaries of every barrister in chambers - be able to offer another suitable barrister in the same chambers who is available to do the next piece of work needed in the client's case. Generally clerks in chambers will concentrate on trying to find a barrister within the chambers they work for who can do the work, and only if they cannot find an available barrister in their own chambers will they suggest other chambers the client could try, but the client can engage any barrister they choose, in any chambers, who is able and willing to do the next piece of work, required in their case.