Dear Andy,
Your pics appear to cover three seperate adult birds. The last one [same bird in pic 3 and 4] is straightforward Heuglin's with ongoing moult of its outer primaries, yellow legs, moderate head streaking and relatively dark mid-grey mantle.
The other two are not so straight forward. Pic 2 also has ongoing wing moult which is in favour of Heuglins but it appears to have dull pink legs and whitish tips to the grey tongues on the upperwing where they meet the black primary tips - both of these are Vega features and hence are signs of a hybrid.
Your first bird in pic 1 is also not straightforward Heuglin's and is closer to Vega [indeed it could be a Vega]. This is because it appears to have pink legs, has completed its wing moult, and has pale tips to the grey tongues on the outer upperwing like the bird in pic 2. Note it also has stronger head and streaking which points more to Vega, but there is considerable overlap. Note the black on both mandibles is a feature of a few Vega but could also indicate a young adult as it appears to have a few dark markings left in the tail as well.
Mike Chalmers
