A rather stupid decision where its implications have not been thought through by UK Govt.
Uk company doing business in another member state where has a tiny market share can find itself being subject to that countrys takeover rules based on what UK CC are doing on precedence. Does City of London really want to find taleovers orchestrated by it held up because Estonia Govt body wishes to have an input?
EU is arbitrator of competition rather than selective Govt bodies with vested interests to remove self interest of Govt.
Funny how BA buying BCAL / BMI etc etc was never a threat to competition nor were there any competitive issues with BAA having majority of London airports until day it was bought by Ferrovial.