(TinyURL is working for me again) RN - tinyurl.com/4shwjnd3tinyurl.com/2k36wsya Also see lateral recruitment to/from Australian forces et al. Historical links between the services are very strong, of course.

Historically - you've got regimental links, links between ships & links between squadrons. The latter, for instance, saw some squadrons bear the name of Commonwealth territories (also see 75 Squadron's permanent transfer to the RNZAF to honour the unit's service in WW2)