This happened where my partner worked (geothermal power station in NZ). She was hired as an electrical engineer about 5 years ago at 22 and was the youngest engineer, along with a group of seven other recient grads. But outside this the next youngest guys are in there mid 50's (some now in their 60's), basically what happened was that the company was privatised from govt control in the 1980's the company decided to stop the practice of hiring new people and training them, and suddenly realised that shit soon all their engineers were going to retire soon so they better get on to that....
To add salt to the wound, the company restructured reciently and my partner was made redundant, not because she wasn't any good but because the company didn't want to pay out the guys with massive retirement/redundancy packages that had been there 35+ years.
As soon as here redundancy was confirmed she rang an old boss from a summer job and had a job offer the next day.