Re the Maidstone William, he entered the Coastguard Service on 12 October 1849 having been nominated from HMS Calypso, with a first posting to Salcombe CG Station. On 12 June 1860 he was transferred to Hope Cove, then on 22 May 1863 to Rochester in Kent, where on 18 November 1865 he was promoted to Commissioned Boatman (a petty officer in the CG Service). He was pensioned from Rochester on 6 July 1869.
While working at Salcombe he re-entered the Navy as one of the 2600 Coastguards recalled for service during the Crimean War, where he served on HMS Duke of Wellington, being awarded the Baltic Medal. It is also probable that he had seen active service before on HMS Harlequin during the 1st China War - if you are able to confirm this I would be grateful.
On the later CG records his date of birth is given as 19 January 1821, and from the BDM Index he looks to have died in the Oct-Dec qtr of 1879 in the Maidstone Reg. District. Following the death of his first wife he married an Elizabeth Carter in the July-Sept qtr of 1865.
In the National Archives is an entry for William and Sarahs son William Edwin, who was sent to the Greenwich Hospital School (ADM 73/196/91). On the application reference is made to Emma, Frances and Lora. Additionally there is a possible pension application for William (ADM 29/59/383), if Im correct this will list his previous service prior to joining the CGs. Both these documents can be ordered online, but are not available as instant downloads.
Hope there is some new information here.
Martin