From Michel and our friend Graham Tanner on UDXF:
05206.0 KK, KI w CONTROL / exercices NATO ? 0619 USB eng ( german & uk accent ) d/x 10jun10 Michel
It is a 'Thursday War' frequency. Every Thursday the Royal Navy and other NATO naval forces have a large exercise in 'La Manche' between Brittany/Normandy and Cornwall/Devon. As would be expected, all the vessels use codes rather than their ship-names, but you can usually work out the nationality of the ship from the accent on the radio.
Graham Tanner