 Additionally, a significant part was made up of refugees and exiles from German-occupied Europe and American emigrants.The RAF Roll of Honour recognises that 574 pilots, from countries other than the United Kingdom, as flying at least one authorized, operational sortie with an eligible unit during the period between 10 July to 31 October 1940, alongside 2,353 British pilots.The numbers differ slightly from the participants whose names are engraved on the Battle of Britain Monument in London, unveiled on 18 September 2005.