Thanks Martin. I am home so I had another look at the burial record. He was buried on the 7th April 1862 at Hubberston. The ceremony was performed by the Chaplain of the HMS Blenheim, the surname is difficult to read but it looks like John W Bursell, Bushell or something similar. John's occupation was described as a "Sailor of the HMS Blenheim". According to the 1861 Census, he was a Seaman (Merchant), along with his brothers Thomas and George; his father Thomas was a Master Mariner.
According to his burial record, the cause of death, which is also difficult to read, reads something like "Killed by a (unreadable) setting of a boat by the Great Eastern". The word "setting" may not be correct.
I am still looking, I am hoping that the Pembroke newspapers that come online in the future might also provide some answers!!!
Kelly