Stamford Baron St Martin is a former civil parish, now in the parish of Stamford, in the South Kesteven district, in the county of Lincolnshire, England.

The Baron part of the name comes from the fact that the area was granted as a barony to the Abbot of Peterborough in the 15th century.

[3] In 1836 Stamford was reformed to become a municipal borough, at which point the municipal boundaries were adjusted to match the recently enlarged constituency.

[5] When elected county councils were established in 1889 boroughs were no longer allowed to straddle county boundaries, and so the part of the parish which was inside the borough of Stamford was transferred to Lincolnshire (becoming part of Kesteven), whilst the more rural rest of the parish remained in Northamptonshire (as part of the administrative county of the Soke of Peterborough).

[8] St Martin's Without and Wothorpe still exist as civil parishes, now in the City of Peterborough unitary authority area of Cambridgeshire.