Robert de Sigello was a medieval Bishop of London

Bishop of London

The Bishop of London is the ordinary of the Church of England Diocese of London in the Province of Canterbury.The diocese covers 458 km² of 17 boroughs of Greater London north of the River Thames and a small part of the County of Surrey...

 and Lord Chancellor of England.

Life

Robert was keeper of the king's seal, usually known as Lord Chancellor

Lord Chancellor

The Lord High Chancellor of Great Britain, or Lord Chancellor, is a senior and important functionary in the government of the United Kingdom. He is the second highest ranking of the Great Officers of State, ranking only after the Lord High Steward. The Lord Chancellor is appointed by the Sovereign...

 from 1133 to 1135. He at one point was a monk at Reading Abbey

Reading Abbey

Reading Abbey is a large, ruined abbey in the centre of the town of Reading, in the English county of Berkshire. It was founded by Henry I in 1121 "for the salvation of my soul, and the souls of King William, my father, and of King William, my brother, and Queen Maud, my wife, and all my ancestors...

, where he may have forged charters in favour of the abbey.

Robert was nominated to the see of London by the Empress Matilda

Empress Matilda

Empress Matilda , also known as Matilda of England or Maude, was the daughter and heir of King Henry I of England. Matilda and her younger brother, William Adelin, were the only legitimate children of King Henry to survive to adulthood...

and consecrated in 1141, possibly about July. He died in 1150, and as his death was commemorated on both 28 September and 29 September, he probably died on one of those dates in 1150.