Football Chap
A player may be registered on List B if he is born on or after 1 January 2002 and since his 15th birthday has been eligible to play for the club concerned for any uninterrupted period of two years,
or a total of three consecutive years with a maximum of one loan period to a club from the same association for a period not longer than one year. Players aged 16 may be registered on List B if they have been registered with the participating club for the previous two years without interruption.
I think bit in bold must be a relatively recent change !