Ah, the good old 20th TFW out of Upper Heyford. They were flying F-111Es. We had F-111Fs at Lakenheath with the 48th TFW. Heyford also had the EF-111 Ravens. I actually met a guy when in Ventura California that was at Heyford when I was at Lakenheath. Small world. Thanks!
It's because that one there is a Bomber variant - you'd have probably seen the AEW variants that don't have the nose turret because it's a RADAR instead.