I would also check out the surnames Pegg in Chesham and John Garrett on the A2A website where record offices are using lottery money to index some of their holdings. The Centre for Buckinghamshire Studies holds quite a few records - mostly mortgages but Hertfordshire Record Office holds these documents
ASHRIDGE II COLLECTION
Catalogue Ref. AH 1-AH 2821
Creator(s):
Egerton family, Earls of Bridgewater
Cust family, Barons Brownlow
Sunnyside (Northchurch)
FILE - Copy of Court Roll: Halimote of Northchurch. - ref. AH 83 - date: 15th October 1781
Admittance of John Garrett of Chesham, Bucks., on death of mother, nee Sarah Foster.
FILE - Copy of Court Roll: Halimote of Northchurch, Honour of Berkhamsted. - ref. AH 93 - date: 18th October 1799
Admittance of William Garrett on death of father, John Garrett.
FILE - Copy of court Roll: Halimote of Northchurch, Honour of Berkhamsted. - ref. AH 135 - date: 25th October 1858
Admittance of John Garrett of Chesham, esq., on death of brother William Garrett. Close called Shaurlings, 7a., abutting West on Gregory's Lane, North, East, and South on lands late Gregory now Darvill.
FILE - Covenant to surrender. - ref. AH 138 - date: 13th August 1860
Garrett of Chesham, esq., to Rt. Hon. Edw. James, Earl of Powis; Rt. Hon. James Walter, Earl of Verulam, and Rt. Hon. William Tatton, Baron Egerton.
Signature - John Garrett
Plus the National Archives holds two Garret PCC wills from Chesham
Will of Timothy Garrett, Gentleman of Chesham, Buckinghamshire 05 September 1749 PROB 11/773
Will of Edward Garrett, Gentleman of Chesham , Buckinghamshire 23 September 1819 PROB 11/1620
Regards
Valda