Our report today reveals the damage threatened to Greenwich Park by the equestrian events of the 2012 Olympics. The choice of one of south-east London's relatively rare green spaces has drawn opposition from local residents, environmentalists and those with an interest in preserving the oldest enclosed royal park in England. Even many within the sport believe that it would be better accommodated at an existing, purpose-built venue such as Badminton or Hickstead. At previous Games, equestrian events have typically taken place far from the main site; sailing, rowing and canoeing will take place outside London in 2012.

At a time of concern about cost, the London Organising Committee should at least tell us why it is not considering a purpose-built venue instead of planning to construct one in Greenwich. Hopes of opening the sport up to a wider audience will only be met if large numbers are allowed to spread around the course, as they do at Badminton. We need to know whether security concerns will permit this.

There are considerable risks involved in using this historic park. The cross-country course will need to be half the standard width in order to avoid trees. Even though the organisers have now promised not to fell any trees, branches will need to be pruned, while roots may also suffer. The organisers must clarify their ill-defined promises of "minimal complete closures", beginning in 2010. And there must be a binding public commitment to fell no trees, and to avoid any construction work that might jeopardise them. The Games's promise of a legacy for London will be marred if this great park suffers permanently.