Well said backpacker. Scottish Info use 7401 in the same way as London use 1177. There are other "conspicuity codes" too, like 7010 for traffic operating in the circuit. There is a list of all the UK allocated squawks in this part of the AIP:
http://www.nats-uk.ead-it.com/aip/cu...ENR_1_6_en.pdf (It also has details of the ATSOCAS etc.)