A routine High Seas Firing (HSF) exercise, nothing unusual about it. Now the Harpoon firings from B52s were something of a different order, We did things properly in the old days and even used real ships as targets!
Although I have not looked for the NOTAM or Notice to Mariners, it is highly unlikely that it was conducted in territorial waters, therefore the press report is correct when it states it was "off Scotland".
High Seas Firings were not uncommon, I was involved in quite few and I suppose that I can claim to have played a part in the final demise of 3 of HM's ships, Undaunted, Cleopatra and Porpoise(?). Undaunted was the most interesting; held in the Atlantic West of Gibraltar (a long way West); it was the target for an Exocet from HMS Norfolk. If the Exocet did not sink the vessel the secondary objective was a Sea Slug launch against it. Now Sea Slug was a large surface to air missile and when its surface to surface profile was described; along with the enormous safety trace; the reaction from our side of the table was "You're going to do what!"
For the record it missed, but made an impressive splash. Undaunted was finally finished off by torpedo from one of HM submarines.