Thankyou Trystan
The file was too large at the first attempt, so I shrunk the file size with GIMP and had another go. I can't make out the person's title on the envelope, but this is what I found so far:
Most Ilfracombe hotels were occupied by the military and civil servants, during WW2.
It's quite reasonable to assume that the addressee/service person was resident at the Royal Clarence Hotel in 1942, either as an officer or as a member of staff.
I have found a National Archives reference to 383 Field Battery RFA (WW2)
Reference: NA WO 166/1612.
The Honourable Artillery website and other sources came up with this:
383 Heavy Anti-Aircraft Regiment Bty (HAA) joined 86th (HAC) in February 1941.
383 may have a been a RA Searchlight Battery and this was the year of the Baedeker Raids.
https://www.iwm.org.uk/history/what-were-the-baedeker-raids.
86th (Honourable Artillery Company) Heavy Anti-Aircraft Regiment RA consisted of 273, 274 and 275 Batteries ; 383 Battery was added in February 1941.
ROYAL ARTILLERY: SEARCHLIGHT BATTERIES: 383 Battery.
UKNA Reference WO 166/7854.
86th (Honourable Artillery Company) Heavy Anti-Aircraft Regiment RA apparently provided officer training, and supplied officers to the British Army.
On 1 December 1942, 86th (HAC) HAA Rgt was formally transferred from AA Command to Home Forces, and moved to Mushroom Farm Camp, Wethersfield, Essex. Until February its batteries were loaned out to AA Command Gun Defence Areas (GDAs) at Norwich, Lincoln and York.
That's all I have