it has been a long time since a non TCAS UK Military aircraft has been over there.
No it hasn't. An MR2 was over there about Easter time. It flew partway down the East Coast of the USA, including through New York Zone, quite happily.
With regard Germany, even though they have withdrawn the State Exemption, I understand MR2 has a waiver for the current year. An MR2 also went there quite recently.
None the above negates the fact that not fitting MR2 with TCAS when it was requested quite a few years ago (using the usual argument that it was due out of service soon), was a bl00dy crass decision.