What I used to do here in Oxford was I had an old portable scanner I would put I think it was tower 7A and 7B base freqs in the scanner. I would put both channels in about 20 channels. It would go 7A,7B,7A,7B so when I heard the squawking sound I would just have to hit the manual button and I would hear London Comm Centre. In my main base and mobile scanner I would enter the mobile freqs. Hopefully you are on a two channel tower up in your neck of the woods.
I must say it was "nice" to hear that squawking noise once again
I must say it was "nice" to hear that squawking noise once again