And links back to the pubwiki – the best site for Essex pub history and lots of regular updates
Oak inn, Messing, Kelvedon – Henry Hart
Oak, Great Saling, Braintree – Walter Mortier
Oak, Forest, Hatfield, Harlow – Mrs. Martha Patmore
Old Bell, Birchanger, Bishops Stortford – Edward Charles Blake
Old Chequers, Barking Side, Ilford – James Deveson
Old Cock, Sheering, Harlow – James Smith
Old Crown, Sandon, Chelmsford – Thomas Nunn
Old Dog, East Horndon & Heron gate. Brentwood – Henry Tanner
Old Green Dragon, Shenfield, Brentwood – John Frederick Howard
Old Maypole, Barking Side, Ilford – George Deveson
Old Royal Oak, 11 Tindal street, Chelmsford – Albert Coombs
Old Ship, West Thurrock, Grays – Thomas Baldwin
Old Ship inn, Aveley, Purfleet S.O. – William John Patten
Old Ship, Debden, Saffron Walden – William James Tant
Old Ship hotel, Rochford S.O. – John Walker
Old Star, Good Easter, Chelmsford – Robert B. Abbott
Old Thatched House commercial hotel, Epping – Mrs. Elizabeth Basham
Old White Hart, 10 Moulsham street, Chelmsford – Arthur May
Old White Horse, North Ockendon, Romford – Abraham Beckwith
Onley Arms, Stisted, Braintree – Albert Earle
Orange Tree inn, Cattle market, Braintree – John Thos. Ainsworth
Orange Tree, Havering-atte-Bower, Romford – Charles Alfred Parrish
Ordnance Arms, High Bridge street, Waltham Abbey – Miss Susannah Brasier
Ordnance Arms, 1 Hythe Quay, Colchester – Mrs. Anne Shead
Osborne Hotel (The), Rosemary road, Clacton-on-Sea R.S.O. – Robert Malcolm Brown
Owl (The), Lippitts hill, High Beech, Loughton S.O. – James Henry Langdon
Oyster Smack, Burnham S.O. – Samuel Cooch