The Templars did not have any large estates in Northamptonshire, but at the start of 1308 they did have a number of tenants scattered across twenty-one locations in that county, who each held a small area of land and perhaps a mill too, and paid regular rent: a list survives in the National Archives at SC 12/13/47. Rent was generally paid on two days of the year: 25 March and 29 September, although one pair of tenants at Great Houghton also paid rent on St John’s Day in midsummer. Total rent due from the tenants in Northamptonshire amounted to £11 16 s. 8½ d., plus two hens and a cockerel at Christmas from one tenant in Aldwinkle. This was not big money: to put it into some perspective, total income after expenses at the commandery of Garway in Herefordshire for the nine months from 10 January to 29 September 1308 was £31 13 s. 10 d — that is, nearly three times as much as income from Northamptonshire in just three quarters of the time.
So, who were these Northamptonshire tenants? Were they just small freeholders or were they larger landowners who happened to be renting land from the Templars as part of their wider estates? A few preliminary searches on the National Archives catalogue suggests that at least some came into the second category, but this is for further research.
Update on 15 December 2015: I’ve now added a translation to my transcription of this rental on Wattpad.
Update on 12 January 2016: I have now transcribed and translated the enrolled accounts recorded at the Exchequer for Northamptonshire. These are inserted at the end of the Oxfordshire, Berks. and Wilts. accounts for 1311–12, 1312–13 and 1313–14, and simply summarise the rent received. They show that the total rent remained the same each year, except in the final few months before the property was handed over to the Hospitallers — when nothing was paid at all. TNA E 358_18-20 accounts for Northants 1311-14
Update on 11 February 2016: the accounts for the Templars’ estates in Bedfordshire during April–July 1308 also include some accounts for Templar property in Northamptonshire at Easton Maudit and Bozeat. I have put a transcription and translation here.