RAF Herks with modified nav lights

I live near RAF Lynham – home of the C-130 fleet and occasional Globemaster jets – and two Herks flew over tonight at low level heading into the military practice area (Salisbury Plain) with flashing nav-lights (i.e. Red, Green, White position lights). These have to be steady lamps in civil aviation but these C-130s had these three nav lamps fading from off to on in standard one second period.

A C-17 flew over low at the same time (practicing dark approaches to RAF Keevil) and this had normal ‘steady’ nav lights. Naturally both types have anti-collision strobes flashing at one second period. It is very strange to see an aircraft with ALL its lights flashing. :confused:

I think there has been a multi-services battle practice on the Plain today so maybe the flashing nav lights are for extra safety when on a practice in the danger area (other aircraft: Chinooks were active there at the same time).

Anybody know the gen on the change to lighting?