Cant comment on your particular sighting Captain but can tell you this. Where I work at Edinburgh we are in close proximity to RAF Leucars. As such we act as a diversionary airfield for them should they go "Black" ie runway blocked or poor weather. Due to the differing types of controlling techniques and traffic patterns employed by civil and military controllers, the pilots will occasionally come in to do practice diversions. This allows us to get used to the higher speeds involved in what might be a surveillance radar approach and the pilots to getting used to fitting into a radar pattern for a possible ILS approach. Dont know for sure but maybe EGNM has a similar set up due to its proximity to RAF Leeming.
As an aside to this for those of you from the Edinburgh area. This is likely to become a more common occurence later this year when Leucars will be having its main runway resurfaced.