The Diocese of London forms part of the Church of England's Province of Canterbury in England. It lies directly north of the Thames. For centuries the diocese covered a vast tract and bordered the dioceses of Norwich and Lincoln to the north and west. The present diocese covers and 17 London boroughs, covering most of Greater London north of the River Thames and west of the River Lea. This area covers nearly all of the historic county of Middlesex. It includes the City of London in which lies its cathedral, St Paul's, and also encompasses Spelthorne which is in modern-day Surrey. The Report of the Commissioners appointed by his Majesty to inquire into the Ecclesiastical Revenues of England and Wales (1835), noted the annual net income for the London see was £13,929. This made it the third wealthiest diocese in England after Canterbury and Durham. The historic county of Essex formed part of the diocese until 1846 when it became part of the Diocese of Rochester, after which St Albans and since 1914 forms the Diocese of Chelmsford. Organisation Following the huge growth of the metropolis and its population in the 19th century, successive Bishops of London successfully campaigned for the appointment of several suffragan bishops to assist them in the care of the northern half of what became the County of London and later Greater London. A system of assigning "districts" to these suffragans evolved into an experimental area scheme in 1970. An archbishop's commission on the diocesan arrangements in Greater London was established in 1975 and chaired by Edmund Compton; its report considered but did not recommend forming all Greater London into an ecclesiastical province. Since the formal institution of the London area scheme (the first of its kind) in 1979, the diocese has been divided into five episcopal areas, each of which is the particular responsibility of one of the diocese's suffragan bishops. It is further divided into archdeaconries and deaneries, as shown below. Bishops Under the London area scheme the diocesan bishop, the Bishop of London retains oversight of the two cities of London and Westminster while the four area bishops have responsibility in their own episcopal areas. The suffragan see of Stepney was created in 1895, Kensington in 1901, Willesden in 1911 and Edmonton in 1970. The suffragan see of Marlborough existed from 1888 to 1918. On 1 May 2015, it was announced that Richard