| School | HMC Division | Membership | Location | Age Range |
| St Bede’s College | North West (UK) | British Isles | Manchester, United Kingdom | 3 - 18 |
| St Benedict’s School | London (UK) | British Isles | London, United Kingdom | 3 - 18 |
| St Catherine’s British School | International | International | Athens, Greece | 3 - 18 |
| St Christopher’s School | International | International | Isa Town, Kingdom of Bahrain | 3 - 18 |
| St Columba’s College, Dublin | Irish | British Isles | Dublin, Republic of Ireland | 12 - 18 |
| St Columba’s College, St Albans | East (UK) | British Isles | St Albans, United Kingdom | 4 - 18 |
| St Columba’s School, Kilmacolm | Scottish (UK) | British Isles | Kilmacolm, United Kingdom | 3 - 18 |
| St Dunstan’s College | London (UK) | British Isles | London, United Kingdom | 3 - 18 |
| St Edmund’s College | London (UK) | British Isles | Ware, United Kingdom | 3 - 18 |
| St Edmund’s School, Canterbury | South East (UK) | British Isles | Canterbury, United Kingdom | 3 - 18 |
| St Edward’s School | South Central (UK) | British Isles | Oxford, United Kingdom | 13 - 18 |
| St George’s College | International | International | Quilmes, Argentina | 3 - 18 |
| St George’s College North | International | International | Buenos Aires, Argentina | 3 - 18 |
| St George’s College Weybridge | London (UK) | British Isles | Addlestone, United Kingdom | 11 - 18 |
| St George’s College, Zimbabwe | International | International | Harare, Zimbabwe | 13 - 18 |
| St George’s British International School, Rome | International | International | Rome, Italy | 3 - 18 |
| St Helen and St Katharine | South Central (UK) | British Isles | Abingdon, United Kingdom | 9 - 18 |
| St Helens’s School | London (UK) | British Isles | Northwood, United Kingdom | 3 - 18 |
| St John’s School | South East (UK) | British Isles | Leatherhead, United Kingdom | 11 - 18 |
| St Julian’s School | International | International | Carcavelos, Portugal | 3 - 18 |
| St Lawrence College | South East (UK) | British Isles | Ramsgate, United Kingdom | 11 - 18 |
| St Leonard’s College | International | International | Melbourne, Australia | 3 - 18 |
| St Leonards | Scottish (UK) | British Isles | St Andrews, United Kingdom | 5 - 18 |
| St Margaret’s School, Bushey | London (UK) | British Isles | Bushey, United Kingdom | 2 - 18 |
| St Mary’s Calne | South West and Wales (UK) | British Isles | Calne, United Kingdom | 2 - 18 |
| St Mary’s College | North West (UK) | British Isles | Liverpool, United Kingdom | 0 - 18 |
| St Mary’s School, Ascot | London (UK) | British Isles | Ascot, United Kingdom | 11 - 18 |
| St Michaels University School | International | International | Victoria, Canada | 3 - 18 |
| St Paul’s School, Brazil | International | International | São Paulo, Brazil | 3 - 18 |
| St Paul’s Girls’ School | London (UK) | British Isles | London, United Kingdom | 11 - 18 |
| St Paul’s School | London (UK) | British Isles | London, United Kingdom | 7 - 18 |
| St Peter’s School | North East (UK) | British Isles | York, United Kingdom | 2 - 18 |
| St Swithun’s School | South Central (UK) | British Isles | Winchester, United Kingdom | 11 - 18 |
| Stockport Grammar School | North West (UK) | British Isles | Stockport, United Kingdom | 3 - 18 |
| Stonyhurst College | North West (UK) | British Isles | Clitheroe, United Kingdom | 3 - 18 |
| Stowe School | East (UK) | British Isles | Stowe, United Kingdom | 13 - 18 |
St Bede’s College
Age range
3 - 18
Location
Alexandra Park, Manchester, M16 8HX, United Kingdom
Head’s name
Maria Kemp
St Benedict’s School
Age range
3 - 18
Location
54 Eaton Rise, London, W5 2ES, United Kingdom
Head’s name
Joseph Smith
St Catherine’s British School
Age range
3 - 18
Location
Leoforos Venizelou 77, Lycovrissi, Athens, 141 23, Greece
Head’s name
Jon Perriss
St Christopher’s School
Age range
3 - 18
Location
PO Box 32052, Isa Town, Kingdom of Bahrain
Head’s name
Simon Watson
St Columba’s College, Dublin
Age range
12 - 18
Location
Whitechurch, Dublin 16, D16 CH92, Republic of Ireland
Head’s name
Mark Boobbyer
St Columba’s College, St Albans
Age range
4 - 18
Location
King Harry Lane, St Albans, Hertfordshire, AL3 4AW, United Kingdom
Head’s name
Karl Guest
St Columba’s School, Kilmacolm
Age range
3 - 18
Location
Duchal Road, Kilmacolm, Scotland, PA13 4AU, United Kingdom
Head’s name
Victoria Reilly
St Dunstan’s College
Age range
3 - 18
Location
Stanstead Road, Catford, London, SE6 4TY, United Kingdom
Head’s name
Nicholas Hewlett
St Edmund’s College
Age range
3 - 18
Location
Old Hall Green, Ware, Hertfordshire, SG11 1DS, United Kingdom
Head’s name
Matthew Mostyn
St Edmund’s School, Canterbury
Age range
3 - 18
Location
St Thomas Hill, Canterbury, Kent, CT2 8HU, United Kingdom
Head’s name
Edward O'Connor
St Edward’s School
Age range
13 - 18
Location
Woodstock Road, Oxford, OX2 7NN, United Kingdom
Head’s name
Alastair Chirnside
St George’s College
Age range
3 - 18
Location
Guido, Quilmes, Buenos Aires Province, Argentina
Head’s name
To be confirmed
St George’s College North
Age range
3 - 18
Location
General Mosconi, Los Polvorines, Buenos Aires Province, Argentina
Head’s name
To be confirmed
St George’s College Weybridge
Age range
11 - 18
Location
Weybridge Road, Addlestone, Surrey, KT15 2QS, United Kingdom
Head’s name
Rachel Owens
St George’s College, Zimbabwe
Age range
13 - 18
Location
Borrowdale Road, Harare, Zimbabwe
Head’s name
John Farrelly
St George’s British International School, Rome
Age range
3 - 18
Location
Via Cassia km16, La Storta, 00123 Roma RM, Italy
Head’s name
Dr John Knight
St Helen and St Katharine
Age range
9 - 18
Location
Faringdon Road, Abingdon, Oxfordshire, OX14 1BE, United Kingdom
Head’s name
Sarah Rollings
St Helens’s School
Age range
3 - 18
Location
Eastbury Road, Northwood HA6 3AN, UK
Head’s name
Bridget Ward
St John’s School
Age range
11 - 18
Location
Epsom Road, Leatherhead, Surrey, KT22 8SP, United Kingdom
Head’s name
Alex Tate
St Julian’s School
Age range
3 - 18
Location
Quinta Nova, Avenida Jorge V, 2775-588 Carcavelos, Portugal
Head’s name
Paul Morgan
St Lawrence College
Age range
11 - 18
Location
College Road, Ramsgate, Kent, CT11 7AE, United Kingdom
Head’s name
Matthew Brown
St Leonard’s College
Age range
3 - 18
Location
Bunurong Country, 163 South Rd, Brighton East, VIC 3187, Australia
Head’s name
Peter Clague
St Leonards
Age range
5 - 18
Location
The Pends, St Andrews, Fife, Scotland, KY16 9QJ, United Kingdom
Head’s name
Simon Brian
St Margaret’s School, Bushey
Age range
2 - 18
Location
Merry Hill Road, Bushey, Hertfordshire, WD23 1DT
Head’s name
Lara Péchard
St Mary’s Calne
Age range
2 - 18
Location
63 Curzon St, Calne, Wiltshire, SN11 0DF, United Kingdom
Head’s name
Anne Wakefield
St Mary’s College
Age range
0 - 18
Location
Everest Road, Crosby, Liverpool, L23 5TW, United Kingdom
Head’s name
Michael Kennedy
St Mary’s School, Ascot
Age range
11 - 18
Location
St. Mary’s Road, Ascot, Berkshire, SL5 9JF, United Kingdom
Head’s name
Danuta Staunton
St Michaels University School
Age range
3 - 18
Location
3400 Richmond Road, Victoria, BC V8P 4P5, Canada
Head’s name
Jeff Aitken
St Paul’s School, Brazil
Age range
3 - 18
Location
Rua Juquiá, 166 - Jardim Paulistano, São Paulo - SP, 01440-020, Brazil
Head’s name
Titus Edge
St Paul’s Girls’ School
Age range
11 - 18
Location
Brook Green, Hammersmith, London, W6 7BS, United Kingdom
Head’s name
Liz Hewer
St Paul’s School
Age range
7 - 18
Location
Lonsdale Road, Barnes, London, SW13 9JT, United Kingdom
Head’s name
Sally-Anne Huang
St Peter’s School
Age range
2 - 18
Location
St Peter's School, York, North Yorkshire, YO30 6AB, United Kingdom
Head’s name
Jeremy Walker
St Swithun’s School
Age range
11 - 18
Location
Alresford Road, Winchester, Hampshire, SO21 1HA, United Kingdom
Head’s name
Jane Gandee
Stockport Grammar School
Age range
3 - 18
Location
Buxton Road, Stockport, Cheshire, SK2 7AF, United Kingdom
Head’s name
Sarah Capewell
Stonyhurst College
Age range
3 - 18
Location
Stonyhurst, Clitheroe, Lancashire, BB7 9PZ, United Kingdom
Head’s name
Christopher Cann
Stowe School
Age range
13 - 18
Location
Stowe, Buckingham, MK18 5EH, United Kingdom
Head’s name
Anthony Wallersteiner