• 1866 establishments in the British Empire (14 C, 4 P)
• 1866 establishments in England (217 P)
• 1866 establishments in Ireland (1 C, 23 P)
• 1866 establishments in Scotland (44 P)
• 1866 establishments in Wales (38 P)

C

• British companies established in 1866 (13 P)

R

• Railway stations in the United Kingdom opened in 1866 (2 C, 1 P)

A

• Albert Medal for Lifesaving
• Amalgamated Association of Beamers, Twisters and Drawers (Hand and Machine)
• Amalgamated Society of Tailors and Tailoresses
• Amalgamated Society of Woodcutting Machinists
• Aunt Judy's Magazine

B

• Belgravia (magazine)
• Buxton Memorial Fountain

C

• Chamber of Agriculture
• Baron Clermont

D

• Third Derby–Disraeli ministry

E

• East India Association
• Duke of Edinburgh
• Ennis baronets

F

• Fielding & Platt

G

• The Garden (journal)

H

• Hebrew Christian Alliance of Great Britain
• Howard League for Penal Reform

J

• Jack Mill, Clayton

N

• National Secular Society

O

• Operative Bleachers, Dyers and Finishers Association

P

• Pollock baronets

R

• The Reader (weekly)
• Royal Aeronautical Society

S

• St Lawrence and Mary Magdalene Drinking Fountain

U

• United Kingdom Alliance of Organised Trades

W

• Wimbledon Cup