Feeding 5,000 Bangers & Mash

We received a phone call requesting assistance and or, a solution to feed 5,000 guests Bangers, Mash, Peas & Gravy at IMM 2014 over a tightly scheduled serve duration. Having contracted before for high volume catering establishments and Michelin starred chef's (Taste of London) we had a pretty good idea how to cook and hold a main course for 5,000 guests over a 4 hour serve duration.

So how do you heat up and hold 1,000kgs of mashed potato, 15,000 sausages, 200kgs of peas and 180 litres of gravy in just a few hours ? Experience, reliable equipment, and the infrastructure to deliver a solution which we are confident would work.