[MilCom] Kate 20

[clifford.web]

hi to all

im looking for some help with the callsign Kate 20 which was ott the English East Coast early this morning.
this was definatley an American - not sounding like the usual fighter and sounded different to the usual mic on the usual heavy transport ott here. did anybody note this callsign in the USA some time on Thursday?
he was routing to  Mildenhall first and then over the North Sea using Upper air routings.

any help appreciated.

thanks
Cliff
East Coast Of England