.....the info on the web says that the juveniles have a less deeply forked tail than the adults but still forked - perhaps these are what you are seeing and contrasting them with the adults?
CLKD I presume you meant to link to this page which gives the difference between the juveniles and the adults?
http://www.yorkshireredkites.net/index.php/2014-03-31-19-47-33/faqs"How can I tell the difference between an adult and a juvenile Red Kite?
Adult birds have a silver/grey head and a pronounced fork in the tail. Close inspection will show black tips to the tail.
Juveniles are generally paler in colour with their head more brown and the tail is noticeably less forked and in flight do not seem as steady as the adult"
Still forked though!!
Sadly I have only ever seen one red kite fairly close (Dorset/Hampshire - or maybe it was Wilts) and possibly a few in the distance around Stonehenge along the A303. They are rarely seen here in this part of SW England.
Hurdity x