After Traveling back to Norwich Late at Night on Friday, At Diss there appered to be a 4 Car Class 321 waiting at Diss Station operating the 2305 Greater Anglia Service from Norwich to Ipswich. This got me wondering weather this is a regular occurrence and also wether there are any more diagrams apart from the 1702 LST-NRW and 1930 return that utilise a Class 321/360/379 instead of the Normal Class 90 and Mk3