In the UK, it's rare for a civil airport ATC or RFFS to be able to access 121.5; usually ATC wise it's only the ATCC that has it by virtue of the 'Distress and Diversion' cell.
The system usually is that if you have an emergency, you stay on the frequency in use (except when you need to communicate with RFFS) and the controller offloads all other traffic to another frequency.