There's an IGI for the marriage in Marcham (about 3/4 miles away):
15.11.1821 John Chesterman & Amelia Brown.
Jill
Logged
See Surname Interests Table + Major brickwalls: John Frith mge to Fanny, Bucks? c 1798 Bathsheba Boothroyd bp W Yks c1802 John Bishop bp E Yks c1758 Joseph Symonds mg to Sarah, prob Berks c 1735-40 John Horwood mg to Martha, Berks c 1735-40 Sarah Sculler bp Berks area c 1675 Paul Phillips bp Berks/Bucks c 1720 William Newell bp Berks/Bucks/Oxon c 1765 Richard Troughton mg to Jane, Westmoreland c 1732 Mary Simon bp Shrops c.1795
The parish registers for Fyfield - part of North Berkshire until 1974 when it moved to Oxfordshire - have been transcribed and indexed by the members of this society. I've just checked our transcription, and I can't find your John CHESTERMAN marriage therein.
Best wishes.
Paul Gaskell Oxfordshire Family History Society Website : www.ofhs.org.uk