Andy...without being cynical, this 15mm shaft axis out of wack sounds like
'Pub talk' .....in this day and age, digital laser alignment is the norm....[even for British built vessels].........
The HMS Queen Elizabeth QA build records on such matters would have been signed off by a number of Builder Certified and Registered professional Engineers. Such alignment checks during Certification would
also have been physically witnessed by RN Engineers
Shaft seal leakage on sizable vessels 10,000 to 100,000 tonne displacement is not an uncommon occurrence.....just ask any sea going ships Engineer....remember, it was only a $20.00 o-ring that created the catastrophic failure of the US Challenger Space Shuttle
Derek