I think Flybe did, to a degree, have a similar strategy to Porter with their operations out of City airport, where did they quite well
Flybe's operations at LCY, and the LHR services, were an utter calamity. I am not sure where you get the idea that they "did quite well" but they did not. BHD was the only route at LCY which was any good and that only did OK because of an overall deal on airport charges that forced Flybe to fly lots of other LCY routes to generate volume. The rest and particularly EDI-LCY were complete basketcases. If Flybe 2 want to replicate Flybe 1, I hope they have deep pockets.