The cost of operating Dornier 228s into LCY must be atrocious. The last time it was done was 20 years ago by City Air Bus from Humberside and they only survived for a couple of weeks. Even an ATR42 will be rather expensive, given that LCY actively - through pricing - discourages the use of anything smaller than 70 seats.
As we are just at it - with three Dornier 228s scheduled to be in the fleet by the end of 2014, apparently the end is nigh for the Trislander fleet. How many Trislanders are required during peak season to serve ACI-GCI/SOU and GCI-JER/DNR? Cannot be more than four, if at all.