As far as I ever was told, the police like a blank canvas, you do it their way.
You join then subject to your capabilities you choose an SQ and try for acceptance. All on skills and qualifications. Have to do 2years as a pro con first. Unless its changed very recently.
Rapid advancement as in Andrew. I must admit I did not like the Police force as it did not fulfill my expectations as far as job satisfaction is concerned, but its a great career for those who like it.
I was an ex Seaman/ Gunner, but I did re cat before I left.