WP209 was operated by No.2 ATU at Edinburgh from July '55 until November 1960.
1321 Flight at Edinburgh had WZ366 and 367 initially. These transferred to No.138 Squadron when it was decreed that an op. Squadron would drop the bomb, and then to No.49.
'366, captained by S/L EJG Flavell dropped the bomb at Maralinga on 11 October 1956.
I suspect you're referring to the later Blue Steel Valiant trials at Edinburgh however.... which ran from 1957-1963.
(Op Grapple also involved 49 Squadron, and Hubbard used XD818 to drop the first H bomb off Malden Island on 15 May 1957, and a second on 31 May. 49 dropped seven bombs, in all.)
Valiant '204 would have been WP204, which was one of the Blue Steel aircraft at Edinburgh. As were WZ370, 373, 375, and WP204. Another jet, WP206, was involved, but didn't have Blue Steel mods.
WH565 was not a Valiant - in fact NO Valiant used the last three '565'.