An RCDS course usually consists of 90-100 Members from the UK and overseas. The UK Members are drawn from the Royal Navy, Army, and Royal Air Force as well as the Ministry of Defence. Other government departments also attend and have been drawn from the Foreign and Commonwealth Office, Home Office, Department for International Development, Cabinet Office and the Defence Science and Technology Laboratories as well as different police constabularies in recent years.
Overseas Members join RCDS from some 50 countries each year on the basis of invitations sent by the UK Ministry of Defence through diplomatic channels. The majority of Members are from the Armed Forces, with the remaining Members being diplomats, civil servants, or police officers. Private sector and non-governmental organisation participation is also welcomed in the interests of broadening the base of experience and gaining wider perspectives. Nominees will already be in positions of responsibility and they will be selected on the basis of their potential to reach the highest ranks in their parent organisation, either as top decision-makers or as a strategic adviser. Most military Members are of OF5/OF6 rank (Colonel/Brigadier) although a small number of more senior, and occasionally junior, officers are also present. Civilian Members will be of an equivalent grade or status.
All Members should be fluent in the English language. Those who do not speak English as their first language must begin the course with a score of at least 6.5 on the International English Language Testing System scale. An intensive six week refresher package of English language training is available prior to the main course for those who need it. The College also provides English classes, once per week for Members from September to December.
Since 2009, the following countries have sent their senior officers and officials to study at Seaford House:
United Arab Emirates