I find that Grey-chinned is usually the commoner minivet in TPK, and often easy to see well. Compared to Grey-chinned, I find that Scarlet always stands out as looking large and chunky with a short tail and large head - with experience the two species are fairly easy to separate on structure alone. As mentioned before, the useful plumage features are the throat colour (yellow on female Scarlet, grey on Grey-chinned) and the yellow spots on the tertials of female Scarlet.
Bob's bird clearly shows the yellow throat and yellow spots on the tertials, and there is no doubt this is a Scarlet Minivet.
