If I've understood it correctly in the USA the FAA have brought in measures that require all flying models to broadcast their ID. It is a possibility that this will spread to Europe and thence to the UK. In the YouTube link below they talk about Broadcast Modules being manufactured in Europe which are both USA and Europe compliant and note that as the FAA have not yet released details of the requirements that it is not possible for these units to be compliant! However that implies that there is discussion in the EU about these regulations already.
There are 3 categories in the USA which in simplistic terms are:
1) Sites where flying takes place but these are tightly regulated and are limited to educational establishments or "community based organisations"
2) Standard RemoteID for free fliers where the ID has to be in-built into the Tx and the aircraft has to be manufactured under strict conditions (basically drones from DJI etc )
3) the Broadcast Model which will cost flyers a great deal of money to fit additional radio gear into their home built models which will broadcast its GPS position on particular frequencies.
Here is the YouTube link:
Happy watching (just when I am contemplating buying a new radio!)