Sounds like a clear case of brake abuse to me- or inop brake fans. The brakes can get up around 700C if you really hammer them, but that is not really a big problem at LCY. The brake fans work reasonably well, and there shouldn't really be a problem on a 30 minute turnaround. I have arrived at MLW and still not got the brakes past 400C- the key is one firm, even application, not constantly modulating them on and off. Brake temp guage can be a little unreliable at times. We usually let them cool to below 250C before takeoff (in case we have to abort, who needs a brake fire???) Of course just going off the end would solve the brake fire problem...!!!