As a member of the Naval Brigade and an AB he was likely to have been a member of a gun crew, even a Captain of Gun, so he would have had skills very useful in the Army.
As to the Diamond in the Crimea, from an initial search of the Times Digital Archive for naval brigade AND diamond, 1852-1857, there are 33 articles returned from Oct 24, 1854 to Feb 26, 1857examples are:
The Times, Tuesday, Oct 24, 1854; pg. 8; Issue 21880; col B The Black Sea Fleet. (FROM OUR OWN CORRESPONDENT.). Second part of article OffSebastopol Oct 7
Includes “….I told you that a naval brigade had been formed to act on shore, Besides the 1,200 marines who occupy the heights to the east of Balaklava, 1,000 sailors, draughted from different vessels, have been landed, together with the upper deck guns of the London, Albion, Queen, Rodney, and Britania, and nearly all the guns of the Diamond. …”
The Times, Saturday, Oct 28, 1854; pg. 7 The War. The British Expedition., The Siege Of Sebastopol
This long article mentions: Oct 13. Describes the scene on the heights, then mentions “…The sailors’ camp is now formed near the artillery park of the left attack, near the lines of the Third Division. There are about 2000 men on shore. …” it then mentions that Diamond has landed 20 of her 27 guns.
The Times, Tuesday, Nov 07, 1854; pg. 6; Issue 21892; col F The Siege Of Sebastopol.
Report ofdespatches from the London Gazette includes list ofkilled and wounded from the naval brigade for two days to 18 Oct 1854, several from Diamond mentioned by name. Then a report to the Admiralty dated Oct 23, includes: “The naval brigade are doing good service and up to the 20th had a loss of 12 killed and 53 wounded, as per annexed list….”
Many UK Libraries allow you to access the Times Digital Archive [even from home 24/7] but if your outside the UK you’ll have to check your own library organisation.
Let me know if you can’t get access and would like more information. Re Naval Papers ADM.139/51 if there’s any other vessels mentioned or something you you don’t understand I’ll see what I can do.