Jo
I'm sceptical that Edward was ever a Coastguard. It was common for men to enter the CG service from the Royal Navy, but they had to have at least seven years service before being nominated. Since he remains on the census in the same place for the majority of the census years I think it unlikely that he was a Coastguard.
However, this is not to say that he never served in the Navy. Continuous Service was introduced in 1853, but did not become compulsory until 1873. It is therefore possible that he signed up just for one commission during a ten year census period, returning to his old occupation in time for the next census.
Given the public outcry, and shortage of seaman during the Crimean War, he may well have signed up. On the Crimea Medal roll there are two Edward Higgins, one a boy under 18 and the other an Ordinary Seaman 2nd Class (or they could both be the same the same man!). Interestingly there is a note against the second that a Duplicate Medal (Baltic) was presented to him by the Plymouth Veterans Association in 1919.
Martin
Coastguards of Yesteryear