Whilst the active and turbulent cleric William de Manthorpe spent part of his career in East Anglia, there are a number of Lincolnshire connections which appear to link him to the Bourne family, as well as a couple of references that might link him to the village near Grantham.

William de Manthorp was mentioned with John de Goushull as the executor of Robert de Pynchebek, Canon of York (4 May 1316). Pinchbeck lies to the north of Spalding and to the east of Bourne.

There are a number of other references to William in the Calendar of Patent Rolls:

21 March 1317 - William de Manthorpe, chaplain, was one of a number of men charged with assaulting Philip de Caldecote at Great Narynges, Norfolk, and carrying away his goods. The leader was Robert Durgillun (Aguillon?)

1318 - Saturninus Fredoli, staying beyond the seas, has letters nominating William de Manthorpe, chaplain, and Nicholas Michaelis de Spaldyng his attorneys for two years (another reference to Spalding).

6 November 1321 - John de Goushull, parson of the church of Alyngton, going beyond the seas, has letters nominating William de Manthorp and Walter Godard his attorneys for two years.

6 September 1322 - Thomas de Eye, parson of the church of Alyngton, complained that John de Goushull, William de Manthorp, chaplain, Master John de Beby ... and others broke his close and houses at Alyngton, Co. Huntingdon, by night and led away two horses of the price of £10 and carried away his goods and assaulted his servants.

Two preceding references appear to relate to problems associated with management of the absent John de Goushull's property: Alyngton is said to be in Huntingdon but Goushull and Beby are surnames associated with Lincolnshire, and this parish cannot be identified with any parish in Huntingdonshire. Consequently this may be a reference to Allington to the north-west of Grantham, which may link William to the Grantham family - although other references appear to connect him with an area closer to Bourne. However, it seems unlikely that there were two clergymen named William de Manthorpe active in Lincolnshire at this period.

The next two references link William to people with Pinchbeck connections and also to another member of the Goushull family:

28 February 1324 - Master Robert de Pynchebek, prebendary of the church of South Neubald, in the church of St Peter, York, staying beyond the seas, nominated William de Manthorp and Alan de Bereford of Pynchebek his attorneys for two years.

20 June 1324 -William de Manthorp, parson of the church of Cotton, diocese of Norwich, and Alan de Goushull acknowledge that they owe to Master Robert de Pynchebek. The amount was to be levied in default of payment from their lands and chattels and ecclesiastical goods in the county of Norfolk. (Calendar of Close Rolls)

The next references to William reveal that he had achieved sufficient standing to have access to the King:

1 April 1329 -The presentation of Ralph Chivaler to the church of Cotton was revoked. It had been supposed to be void by the death of William de Manthorp but William had "appeared before the King in good health".

On 1 May 1333 William de Manthorp, parson of the church of Cotton in the diocese of Norwich, was appointed to the church of Ouneby in the diocese of Lincoln, on an exchange of benefices with Stephen. This is presumably Owmby, to the north of Lincoln. The parish was in the King's gift.

William's association with the two Robert de Pinchbecks, the Canon of York and the prebendary of South Newbold probably stood him in good stead for forwarding his career in the Church. They presumably belonged to the gentry family of that name that lived in Pinchbeck, not far from Bourne. Members of the Pinchbeck family had already held several senior offices in the church. Likewise, John de Goushull (or Goushill) may have belonged to the gentry family of that name who were based in Hoveringham in Nottinghamshire but who had originated in Goxhill in Lincolnshire. William's lawless zeal in defending Goushull's interests may be another indication of the importance of keeping on good terms with a man from an influential gentry family.

It is not known how long William remained at Owmby; it was presumably there that he closed his unruly but successful career in the Church.