| School | HMC Division | Membership | Location | Age Range |
| Francis Holland, Sloane Square | London (UK) | British Isles | Westminster, London, United Kingdom | 4 - 18 |
| Frensham Heights School | South Central (UK) | British Isles | Farnham, United Kingdom | 3 - 18 |
| GEMS FirstPoint School, Dubai | International | International | دبي, United Arab Emirates | 4 - 18 |
| GEMS Wellington International School, Dubai | International | International | Dubai, United Arab Emirates | 3 - 18 |
| George Heriot’s School | Scottish (UK) | British Isles | Edinburgh, United Kingdom | 4 - 18 |
| George Watson’s College | Scottish (UK) | British Isles | Edinburgh, United Kingdom | 0 - 18 |
| Giggleswick School | North East (UK) | British Isles | Settle, United Kingdom | 2 - 18 |
| Glenalmond College | Scottish (UK) | British Isles | Glenalmond, United Kingdom | 12 - 18 |
| Godolphin School | South Central (UK) | British Isles | Salisbury, United Kingdom | 3 - 18 |
| Gordon’s School | South Central (UK) | Associate (UK) | Woking, United Kingdom | 11 - 18 |
| Gordonstoun | Scottish (UK) | British Isles | Elgin, United Kingdom | 5 - 18 |
| Gresham’s School | East (UK) | British Isles | Holt, United Kingdom | 2 - 18 |
| Guildford High School | South Central (UK) | British Isles | Guildford, United Kingdom | 4 - 18 |
| Haberdashers’ Monmouth School | South West (UK) | British Isles | Monmouth, United Kingdom | 3 - 18 |
| Haberdashers’ Boys’ School | London (UK) | British Isles | Borehamwood, United Kingdom | 5 - 18 |
| Haileybury College | London (UK) | British Isles | Hertford, United Kingdom | 11 - 18 |
| Halliford School | London (UK) | British Isles | Shepperton, Surrey, United Kingdom | 11 - 18 |
| Hampton School | London (UK) | British Isles | Hampton, Richmond upon Thames, United Kingdom | 3 - 18 |
| Harrow International School, Bangkok | International | International | Bangkok, Thailand | 2 - 18 |
| Harrow International School, Hong Kong | International | International | Tuen Mun, Hong Kong | 3 - 18 |
| Harrow School | London (UK) | British Isles | Harrow, London, United Kingdom | 13 - 18 |
| Hereford Cathedral School | West (UK) | British Isles | Hereford, United Kingdom | 3 - 18 |
| High School of Dundee | Scottish (UK) | British Isles | Dundee, United Kingdom | 3 - 18 |
| High School of Glasgow | Scottish (UK) | British Isles | Glasgow, United Kingdom | 3 - 18 |
| Highgate School | London (UK) | British Isles | Haringey, London, United Kingdom | 3 - 18 |
| Hill House School | North East (UK) | British Isles | Doncaster, United Kingdom | 4 - 18 |
| Howell’s School, Llandaff | South West (UK) | British Isles | Cardiff, United Kingdom | 3 - 18 |
| Hulme Grammar School | North West (UK) | British Isles | Oldham, United Kingdom | 2 - 18 |
| Hurstpierpoint College | South East (UK) | British Isles | Hurstpierpoint, United Kingdom | 4 - 18 |
| Hutchesons’ Grammar School | Scottish (UK) | British Isles | Glasgow, United Kingdom | 3 - 18 |
| Hymers College | North East (UK) | British Isles | Hull, United Kingdom | 3 - 18 |
| Ibstock Place School | London (UK) | British Isles | Roehampton, London, United Kingdom | 4 - 18 |
| Immanuel College | London (UK) | British Isles | Bushey, Herts, United Kingdom | 4 - 18 |
| Ipswich School | East (UK) | British Isles | Ipswich, United Kingdom | 3 - 18 |
| James Allen’s Girls’ School | London (UK) | British Isles | Dulwich, London, United Kingdom | 4 - 18 |
| Jerudong International School | International | International | Bandar Seri Begawan, Brunei Darussalam | 2 - 18 |
Francis Holland, Sloane Square
Age range
4 - 18
Location
39 Graham Terrace, London, SW1W 8JF, United Kingdom
Head’s name
Alexandra Haydon
Frensham Heights School
Age range
3 - 18
Location
Frensham Heights Road, Farnham, Surrey, GU10 4EA, United Kingdom
Head’s name
Ben McCarey
GEMS FirstPoint School, Dubai
Age range
4 - 18
Location
The Villa Dubai, Dubai Al Ain Road, Dubai, United Arab Emirates
Head’s name
David Wade
GEMS Wellington International School, Dubai
Age range
3 - 18
Location
Al Sufouh Area, Sheikh Zayed Road, Dubai, United Arab Emirates
Head’s name
Maryssa O'Connor
George Heriot’s School
Age range
4 - 18
Location
Lauriston Place, Edinburgh, Scotland, EH3 9EQ, United Kingdom
Head’s name
Gareth Warren
George Watson’s College
Age range
0 - 18
Location
Colinton Road, Edinburgh, EH10 5EG, United Kingdom
Head’s name
Lisa Kerr
Giggleswick School
Age range
2 - 18
Location
Giggleswick, Settle, North Yorkshire, BD24 0DE, United Kingdom
Head’s name
Sam Hart
Glenalmond College
Age range
12 - 18
Location
Warden's House, Glenalmond, Perthshire, Scotland, PH1 3RY, United Kingdom
Head’s name
To be confirmed
Godolphin School
Age range
3 - 18
Location
Milford Hill, Salisbury, SP1 2RA, United Kingdom
Head’s name
Jenny Price
Gordon’s School
Age range
11 - 18
Location
West End, Woking, Surrey, GU24 9PT, United Kingdom
Head’s name
Andrew Moss
Gordonstoun
Age range
5 - 18
Location
Gordonstoun, Elgin, Moray, Scotland, IV30 5RF, United Kingdom
Head’s name
Peter Green
Gresham’s School
Age range
2 - 18
Location
Gresham's School, Holt, Norfolk, NR25 6EA, United Kingdom
Head’s name
Douglas Robb
Guildford High School
Age range
4 - 18
Location
London Road, Guildford, Surrey, GU1 1SJ, United Kingdom
Head’s name
Karen Laurie
Haberdashers’ Monmouth School
Age range
3 - 18
Location
Almshouse Street, Monmouth, Gwent, Wales, NP25 3XP, United Kingdom
Head’s name
Simon Dorman
Haberdashers’ Boys’ School
Age range
5 - 18
Location
Butterfly Lane, Elstree, Borehamwood, Herts, WD6 3AF, United Kingdom
Head’s name
Gus Lock
Haileybury College
Age range
11 - 18
Location
Haileybury, Hertford, SG13 7NU, United Kingdom
Head’s name
Eugene du Toit
Halliford School
Age range
11 - 18
Location
Russell Road, Shepperton, Middlesex, TW17 9HX, United Kingdom
Head’s name
James Davies
Hampton School
Age range
3 - 18
Location
Hampton School, Hampton, Middlesex, TW12 3HD, United Kingdom
Head’s name
Kevin Knibbs
Harrow International School, Bangkok
Age range
2 - 18
Location
45 Soi Kosumruamchai 14, Kosumruamchai Rd, Don Mueang Subdistrict, Don Mueang District, Bangkok 10210, Thailand
Head’s name
James Murphy-O'Connor
Harrow International School, Hong Kong
Age range
3 - 18
Location
38 Tsing Ying Road, Tuen Mun, Hong Kong
Head’s name
Ann Haydon MBE
Harrow School
Age range
13 - 18
Location
5 High Street, Harrow, Middlesex, HA1 3HP, United Kingdom
Head’s name
Alastair Land
Hereford Cathedral School
Age range
3 - 18
Location
Old Deanery, Hereford, Herefordshire, HR1 2NG, United Kingdom
Head’s name
Michael Gray
High School of Dundee
Age range
3 - 18
Location
Euclid Crescent, Dundee, Tayside, Scotland, DD1 1HU, United Kingdom
Head’s name
Lise Hudson
High School of Glasgow
Age range
3 - 18
Location
27 Ledcameroch Road, Bearsden, Glasgow, Scotland, G61 4AE, United Kingdom
Head’s name
John O'Neill
Highgate School
Age range
3 - 18
Location
North Road, Haringey, London, N6 4AY, United Kingdom
Head’s name
Adam Pettitt
Hill House School
Age range
4 - 18
Location
Sixth Avenue, Doncaster, South Yorkshire, DN9 3GG, United Kingdom
Head’s name
David Holland
Howell’s School, Llandaff
Age range
3 - 18
Location
Cardiff Road, Cardiff, Wales, CF5 2YD, United Kingdom
Head’s name
Sally Davis
Hulme Grammar School
Age range
2 - 18
Location
Chamber Road, Oldham, Lancashire, OL8 4BX, United Kingdom
Head’s name
John Budding
Hurstpierpoint College
Age range
4 - 18
Location
College Lane, Hurstpierpoint, West Sussex, BN6 9JS, United Kingdom
Head’s name
Dominic Mott
Hutchesons’ Grammar School
Age range
3 - 18
Location
21 Beaton Road, Glasgow, Scotland, G41 4NW, United Kingdom
Head’s name
Mark Ronan
Hymers College
Age range
3 - 18
Location
Hymers Avenue, Hull, HU3 1LN, United Kingdom
Head’s name
Justin Stanley
Ibstock Place School
Age range
4 - 18
Location
Clarence Lane, Roehampton, London, SW15 5PY, United Kingdom
Head’s name
Christopher Wolsey
Immanuel College
Age range
4 - 18
Location
Elstree Road, Bushey, Herts, WD23 4EB, United Kingdom
Head’s name
Daniel Endlar
Ipswich School
Age range
3 - 18
Location
25 Henley Road, Ipswich, Suffolk, IP1 3SG, United Kingdom
Head’s name
Nick Gregory
James Allen’s Girls’ School
Age range
4 - 18
Location
144 East Dulwich Grove, London, SE22 8TE, United Kingdom
Head’s name
Alex Hutchinson
Jerudong International School
Age range
2 - 18
Location
Jalan Universiti, Bandar Seri Begawan BE 2119, Brunei Darussalam
Head’s name
Nicholas Sheehan