2 Sheds
IIRC Scratcoh came about due to pressure being applied by GATCO, which was concerned at the excessive hours being worked at several 'non-state' ( sorry chaps of a sensitive nature! ) airfields, particularly with a new provider.
At Heathrow we worked MMAANN or MMAADD - a D1 would start at 0800 following the previous afternoon finishing at 2200. Which was great for those rostered on D1 as their days off started generally at 1430 on the second day shift into 4 whole days off. Being a long distance commuter I was often able to swap shifts and work AMAM, spending the time between A and M sleeping in the dormitory or a spare office. This of course saved on the numbers of journeys to work and the amount spent on fuel!
After Scratcoh that swap option plus AAD1D1 were no longer legal as the new law laid down a minimum break of 12 hours between shifts. It certainly wasn't wanted by us in CAA as it limited personal flexibility.