Seiko has produced quite a few watches for militaries throughout the world over the years, such as the 7A28-7120 and 7T27-7A20 chronographs. The 7A28 and its successor, the 7T27, were known as the British Royal Air Force Gen 1 and RAF Gen 2, respectively, as both were RAF-issued watches - like the full-serviced 1996 Seiko 7T27-7A20 RAF Gen 2 chronograph here.
The 7T27 was a unique movement, featuring a 30-minute register chronograph and 24-hour subdial. Seiko provided the 7A28s to RAF from the early 1980s through late 1990, for a total of 11,307 examples. The subsequent 7T27s came in two variants - first issued was one to the RAF - the example available here - with Promethium-147 lume (signified by an encircled “P” on the dial; Promethium was a mildly radioactive emitter).
Another version was subsequently issued sans luminous markings to the British Royal Navy, primarily for crew on HM nuclear submarines. Presumably, the lack of luminescent meant it could also be used in any environment where luminous material might interfere with sensitive military equipment or interfere with the night vision of the crew; the latter we learned from a former USN Petty Officer 2nd (PO2) Class, who served on a USN fast attack submarine, "The UK Royal Navy version of the 7T27 likely came without lume so as to not interfere with the officer of the deck’s (OOD) night vision. During night hours, the control room of the submarine is rigged for black and only red light was used so if the submarine has to go to periscope depth, the OOD’s eyes are already night adapted."
By the late 1990’s, Seiko ended both the 7A28 and 7T27 (the earlier luminescent version) calibers in favor of the 7T32 alarm chronograph – Seiko went on to produce military-looking 7T32s subsequent, but none were military-issued timepieces. However, in 1993, Seiko did supply the Royal Navy with watches for its submarine crews from 1993 through 2000 in quite small numbers.
This Seiko 7T27 quartz watch comes with three nylon straps, springbar tool, and a rugged travel case.
1996 Seiko 7T27-7A20 UK Royal Air Force-Issued Gen 2 Chronograph
DIAL: Detailed black dial, with unique encircled “P” nomenclature, signifying the presence of Promethium-147 lume. Dial is signed, with Arabic numeral hour markers. Correct handset; lume glows on dial and handset, as designed.
CASE: Stainless-steel bead-blasted case measures 38mm (40mm w/crown) x 43mm brushed stainless steel case, with matching caseback. Please note UK RAF military markings on the caseback identifiy this 7T27 as a RAF military-issued watch.
CRYSTAL: Original crystal, no imperfections.
BAND: This UK military-issued Seiko comes with three 20mm nylon straps. Please note this 7T27 has fixed strap bars - common with military-issued watches - so only pass through-style straps will fit.
MOVEMENT: Seiko 7T27 quartz movement, manufactured in June 1996. We have performed a full service on this RAF-issued watch.
CROWN: Unsigned stainless-steel crown.