Not much is found on the JOHN WESLEY. She did belong to the London Missionary Society, but were and by who built unknown so far..
The most likely candidate is the Brig JOHN WESLEY, which sailed from Southampton, and arrived at Auckland on 11 April 1847 under command of Capt. Buck. She came via Sydney.
On board were a group of missionaries.
The next time she sailed from London on 26 September 1851 and arrived after a passage of 120 days on 26 Jan. 1852 at Auckland under command of Capt. John Ryle. During the voyage the son of the captain died.
She arrived with on board 2 missionaries and 12 other passengers.
26 March 1854 the JOHN WESLEY arrived at Sydney from Auckland under command of Capt. John Ryle with on board 13 crew and 18 passengers.
13 November 1857 the brig JOHN WESLEY, registered in London, under command of Capt. Thomas Birkenshaw arrived from the port of Rotuniah, in Sydney, NSW. Australia.
Tonnage is given as 236 tons burthen. Crew 15 and 10 passengers and 3 men from the wrecked brig PILAMON.
24 August 1863 JOHN WESLEY of London arrived at Sydney from ports in the South Seas under command of Capt. James Welch with on board a crew of 16, and 12 passengers.
It is given that she later foundered, but not a date or position given.
Tuvalu 1986 40c sg 378, scott 354
Source: Many web-sites.