Nice report mate. According to the RCAHMS website
http://canmore.rcahms.gov.uk/en/site/36244/digital_images/montrose+airfield+general/
there is still a few pillboxes etc. around the site
NO75NW 31.01 centred NO 7190 5955 Aircraft Hangars
NO75NW 31.02 NO 7184 5911 Pillbox
NO75NW 31.03 NO 7205 5908 Pillbox
NO75NW 31.04 NO 7206 5917 Pillbox
NO75NW 31.05 c.NO 7251 5929 Pillbox
NO75NW 31.06 c.NO 7286 5948 Pillbox
NO75NW 31.07 c.NO 7305 5971 Pillbox
NO75NW 31.08 NO 7215 5996 Operations Block; Pillbox
NO75NW 31.09 NO 7195 5951 Pillbox
NO75NW 31.10 NO 7132 5894 Pillbox
NO75NW 31.11 NO 7185 5947 Pillbox
NO75NW 31.12 c.NO 7170 5976 Pillbox
NO75NW 31.13 c.NO 7289 5959 Operations Block
NO75NW 31.14 c.NO 7292 5974 Pillbox
NO75NW 31.15 NO 7222 5990 Shooting Butt
NO75NW 31.16 NO 71760 59339 Aircraft Hangar
NO75NW 31.17 NO 71764 59263 Aircraft Hangar
NO75NW 31.18 NO 71828 59464 Building
NO75NW 31.19 NO 71894 59501 Aircraft Hangar
NO75NW 31.20 NO 71821 59436 Guard Room
NO75NW 31.21 NO 71819 59312 Aircraft Hangar
NO75NW 31.22 NO 71782 59414 Aircraft Hangar
NO75NW 31.23 NO 7215 5979 Control Tower
NO75NW 31.24 NO 72252 59899 Pillbox
NO75NW 31.25 centred NO 71858 59535 and NO 71958 59675 Aircraft Hangars (Belfast Truss)
NO75NW 31.26 NO 7199 5958 Pillbox
Don't know if they are still there or have been demolished. I think this is the same place