Like I say that's what I have heard on the grapevine, I don't know the staffing levels at EGKK at present - how short are they? How many are they trying to recruit? How many have validated in the last few years? All I know is if I were in a position to be thinking about EGKK and I had heard that there was an unexplained high failure rate then I would have to seriously consider whether I wanted to work in those circumstances. If the failure rate is higher than it previously was then there should be questions asked - namely why? Are the recruits suitable? Is the instruction poor? Is the assessment process unrealistic? It is unimaginable that it was all ticking over with NATS at the helm but yet with the same staff it has went to the dogs with a different ANSP.
The regulator is short staffed as well from what I can see. The airport has signed a contract with a new company to provide ATC services - no doubt there'll be penalty clauses in the contract somewhere to cover all sorts of eventualities, the airport has paid the ANSP to worry about staffing levels and recruitment/retention. I believe there are large financial incentives for the controllers at EGPH to stay with the company, surely the same will apply at EGKK.