Ryanair UK from 1st Jan 2021
Ryanair booking system is being updated with Ryanair UK flight numbers with effect from 1st Jan 2021.
This only applies to a fairly small number of routes from the UK that would otherwise be impacted by Brexit, including UK domestic, Montenegro, Morocco and Ukraine.
From 1st Jan, all flights from the UK to those destinations will operate with "RK" flight numbers and presumably therefore under the ATC callsign "Blue Max".