HD - I think you'll find that Wattisham cover an area from a bit north of Southend, south of Chelmsford, the whole of the Stansted zone, a bit of the Luton zone, Wyton, Ely, Marham, nearly Norwich and all down the East Anglian coast. I know they do radar handovers to Thames, Southend, Essex, Luton, Cambridge, Lakenheath, Marham and Norwich. Even heard them one night pick up a guy from somewhere near LAM & eventually hand them to Cottesmore. Granted, they're rarely open on a weekend but even so... How much do you want?
Luton may be done from TC but it's still Luton. Southend have primary-only but should be getting SSR fairly shortly.
Of course the primary task is always the focus and rightly so, but any spare capacity should be utilised too. Without compromising that task, the best service possible to all comers.
ap