Once upon a time, we had a large army, navy & airforce and consequently lots of engineers doing their time and leaving in their 40s with a service pension.
These people still needed jobs and with a lot of military work being given to private companies, they were snapped up. They were perhaps not on high wages, but with their pensions, they did okay.
Roll on to today and these jobs still exist, but there are now fewer people about to fulfil these roles. As the contracts for this work usually goes to the lowest bidder, companies still want to pay the same sort of salaries. However, there aren’t so many who have the benefit of a pension to boost their take home pay. Skilled engineers are looking elsewhere, where their skills are appreciated and recompensed accordingly.
This issue has been brewing for some time, but it’s been heads in the sand and hoping it would go away. It’ll get worse unless more money is put on the table.