How might the Royal Family have been evacuated?

Would the Royal Family and Royal Navy have evacuated through Pembrokeshire if Britain were invaded?

Pembrokeshire was one possibility alongside Liverpool or Scotland; the king and queen might have stayed, the princesses could have been evacuated, and a complete collapse could send Royal Navy assets to Canada.

Evacuation through Pembrokeshire was a possibility rather than a settled plan. Liverpool or ports in Scotland could also have provided routes out, and the king and queen might not have agreed to leave. The princesses were more plausible evacuees, potentially aboard a fast and well-protected warship if one were available. In the much more extreme case of Britain falling completely, Royal Navy plans called for withdrawing as much as possible to Canada.