The first creation came in the Peerage of England when John de Montfort was summoned to parliament on 23 June 1295.
[1] The second creation came in the Peerage of Great Britain in 1741 when Henry Bromley was made Lord Montfort, Baron of Horseheath, in the County of Cambridge.
The second family descended from the 16th century Lord Chancellor Sir Thomas Bromley and Lord Chief Justice of the same name and were still in the 18th century equally recorded with the alternative spelling and pronunciation Montford.
This is a corruption as 'Montfort' means a fortified mountain or mound as in Montfort l'Amaury, the place of birth of Simon I de Montfort their 11th century French patriarch.
Simon de Montfort, 6th Earl of Leicester led to the first Parliament called to act as a check on the monarch in 1295 and was commonly known as Simon de Montford hence the unusually long continuation in the alternative spelling, see Montfort for examples.