| Equestrian |
1991 European Eventing Championships |
Punchestown |
 IRL |
Team eventing, Open |
🥇 |
 GBR |
as Mary Thomson |
| Equestrian |
1994 World Equestrian Games |
Den Haag |
 NED |
Team eventing, Open |
🥇 |
GBR |
as Mary Thomson |
| Equestrian |
1995 European Eventing Championships |
Pratoni del Vivaro |
 ITA |
Individual eventing, Open |
🥉 |
GBR |
as Mary King |
| Equestrian |
1995 European Eventing Championships |
Pratoni del Vivaro |
ITA |
Team eventing, Open |
🥇 |
GBR |
as Mary King |
| Equestrian |
1997 European Eventing Championships |
Burghley |
GBR |
Team eventing, Open |
🥇 |
GBR |
as Mary King |
| Equestrian |
2006 World Equestrian Games |
Aachen |
 GER |
Team eventing, Open |
🥈 |
GBR |
as Mary King |
| Equestrian |
2007 European Eventing Championships |
Pratoni del Vivaro |
ITA |
Individual eventing, Open |
🥈 |
GBR |
as Mary King |
| Equestrian |
2007 European Eventing Championships |
Pratoni del Vivaro |
ITA |
Team eventing, Open |
🥇 |
GBR |
as Mary King |
| Equestrian |
2010 World Equestrian Games |
Lexington, Kentucky |
 USA |
Team eventing, Open |
🥇 |
GBR |
as Mary King |
| Equestrian |
2011 European Eventing Championships |
Luhmühlen |
GER |
Team eventing, Open |
🥉 |
GBR |
as Mary King |