All these dogmatic comments about “In situation X I always indicate” or “In situation Y I never indicate” are missing the point. You should be assessing the situation around you and signalling if there is a benefit in doing so.
So with regard to this ...
The vehicle you have just overtaken may benefit from the signal, just so they know when you are coming back to the left.
When I was a Driving Instructor I was told by the senior examiner in Norwich when discussing signalling that indicating to pull back into the nearside lane after overtaking on a dual carriageway is unnecessary as the normal lane to drive in is the nearside lane the outside lane is for overtaking, anyone you have overtaken should be aware that you are going to return to that lane when it is safe to do so if there is no traffic in it.
and that's why he's an Examiner !
... even the “senior examiner in Norwich” isn’t 100% correct, because it depends on the circumstances, for example:
- if there’s no other traffic around then he’s right. Although as already stated I might signal anyway just to keep the lane departure warning quiet.
- if there’s a faster vehicle coming up behind as I complete the overtake then I’ll signal to tell him I’m moving over.
- if I’m returning to lane 2 from lane 3 after an overtake then I’ll signal so that vehicles in lane 1 are warned against moving out.