The title Lord Lieutenant is given to the British monarch's personal representatives around the United Kingdom, usually in a county, with varying tasks throughout history. Usually a retired local notable, senior military officer, peer or business person is given the post honourarily. Both men and women are eligible for the post.

Origins

England and Wales
In England and Wales and Ireland, the lord lieutenant was the principal officer of his county. His creation dates from the Tudors.

Lieutenants were first appointed to a number of English historic counties by Henry VIII in the 1540s, when the military functions of the sheriff were handed over to him. He raised was responsible for the efficiency of the local militia units of the county, and afterwards of the yeomanry, and volunteers. He was Commander of these forces and appointed their officers.

Lieutenancies became more organised soon, probably in the reign of his successor Edward VI, their establishment being approved by the English parliament in 1550. It was not until the threat of invasion by the forces of Spain in 1585 that lieutenants were appointed to all counties. After the defeat of the Spanish Armada, the need for lieutenants was reduced — and the lieutenancies of some counties were left vacant in the 1590s.

The three ridings (sub-divisions) of Yorkshire each got their own.

The official title of the office at this time was His or Her Majesty's lieutenant for the county, but as almost all office-holders were peers they were referred to as "lord-lieutenant".

The Twentieth Century
The Territorial and Reserve Forces Act 1907 established County Territorial Force Associations, of which the lord-lieutenant was to be head. So the combination of counties and county corporates as lieutenancy counties was restored.

Local Government reform in England in 1965 led to the appointment of lord-lieutenants to Greater London and Huntingdon and Peterborough, and the abolition of those of the County of London, Middlesex and Huntingdonshire.

A more fundamental reform of local government throughout England and Wales (outside Greater London) created a new structure of metropolitan, non-metropolitan and Welsh counties in 1974. Section 218 of the Local Government Act 1972 that established the new system stated: "Her Majesty shall appoint a lord-lieutenant for each county in England and Wales and for Greater London..." The Act appears to be the first statutory use of the term "lord-lieutenant" for lieutenants to counties.

In 1975 counties ceased to be used for local government purposes in Scotland. The Local Government (Scotland) Act 1973 replaced the counties with regions, and each region was to have one or more lord-lieutenants appointed. The areas to which they were appointed approximated to the counties and were based and were defined in terms of the new local government districts.

Present-day
In 1996 Scottish regions and districts were abolished on further local government reorganisation, and since that date lord-lieutenants have been appointed to lieutenancy areas.

Partial reform of local government in England since 1995 has led to the creation of so-called ceremonial counties to which lord-lieutenants are now appointed. The Lieutenancies Act 1997 is the most recent piece of primary legislation dealing with Lieutenancies in England and includes the definitive list of the current areas used. Ceremonial counties may be comprised of combinations of county council areas and unitary authorities.

Since the local government re-organisation of 1996 in Wales, lord-lieutenants are now appointed to preserved counties.

The City of London was unaffected by changes introduced since 1882. It has a Commission of Lieutenancy rather than a single Lord-Lieutenant. The Head of the Commission is the Lord Mayor of London.

The modern responsibilities of lord-lieutenants include:
 Arranging visits of members of the Royal family and escorting Royal visitors;
 Presentation of medals and awards on behalf of the Sovereign, and advising on Honours nominations;
 Participation in civic, voluntary and social activities with the Lieutenancy;
 Liaison with local units of the Royal Navy, Royal Marines, Army, Royal Air Force and their associated cadet forces; 
 Leading the local magistracy as Chairman of the Advisory Committee on Justices of the Peace; and
 Chairing the local Advisory Committee for the Appointment of the General Commissioners of Income Tax, a tribunal which hears appeals against decisions made by the HM Revenue and Customs on a variety of different tax related matters.

As the sovereign's representative in his or her county, the Lord-Lieutenant remains non-political and holds no office in any political party.  The usual age of retirement is 75.  They are appointed for life, although the sovereign may remove them.

The Lord-Lieutenant is supported by a Vice Lord-Lieutenant and Deputy Lieutenants which he or she appoints. 
They are unpaid, but receive minimal allowances for secretarial help, mileage allowance and a driver. Male Lord-Lieutenants receive an allowance for the ceremonial uniform, worn when receiving members of the royal family and on other formal occasions.

There is no uniform for a female Lord-Lieutenant, but there is a badge which can be worn on ceremonial occasions. Male Lord-Lieutenants wear a dark blue uniform in the style of an Army No. 1 dress along with a cap and sword with a steel scabbard. The uniform for a male Vice Lord-Lieutenant and Deputy Lieutenants is of a similar style, but with features to distinguish it from a Lord-Lieutenant.

Lord Lieutenant of Ireland
The Lord Lieutenant of Ireland was the head of the British administration in Ireland until the foundation of the Irish Free State in 1922.

Correct forms of address for the Lord-Lieutenant 
Written: '(Title and name), Lord-Lieutenant'
Salutation: 'Dear Lord-Lieutenant' 
In a Speech: 'My Lord-Lieutenant' 
In conversation: '(Title and name)' or 'Lord-Lieutenant'.

Related pages
Ceremonial counties of England

References

Sources and Other websites

Royal website on Lord-Lieutenant
Website of the Lord Lieutenant of South Yorkshire 

British monarchy