The original RN Sea King HAS1 didn't have a rear view mirror, but they were added (IIRC) about 1972. Checks required a visual confirmation that the gear was down (2 greens didn't cut it!), and it was difficult to get a Mk 2 or Mk 3 bone dome out of the sliding window to look. Hence the mirrors, which also became handy to check the intakes (pre barn door mod), etc. If they were still there, it could also be assumed that the engines were also attached
