Shibden Valley

Four days ago I saw a Lesser Whitethroat next to Kell Lane - about 100m north of where I saw one in 2017. It was in a large hawthorn west of the road, about 50m above where Staups Lane joins Kell Lane.
My experience makes me think that descriptions of this species in guide books leave something to be desired, and I'd be interested to know what other bloggers think.
Vinicombe et al (The Helm guide to bird ID) say that the head is grey, often with darker lores and ear coverts, the upperparts are grey-brown, and the underparts appear clean silky-white. Svensson et al (Collins bird guide) say the bird is always grey-brown above with greyer crown and tail, and darker grey ear coverts - darker than crown; and their pictures show buff underparts. Neither mentions any difference between the sexes.
My bird was small and very active, making it difficult to see all its features (I didn't see the legs, for example). It stayed in the bush, and after maybe a minute flew off - when the white sides to the short tail were clearly seen.
The sun was shining, and to me the cap and ear coverts both looked light to mid-brown - with no difference in colour. The upperparts were mid-brown, and the underparts a clean light buff (not "silky-white"). I didn't see a whiter throat, but cannot exclude this. And I didn't see any grey in the upperparts.
There are several races of Lesser Whitethroat worldwide, but I have to assume that in Calderdale in spring I'm looking at the W European race.
In the past I have seen Lesser Whitethroats that fit the above textbook descriptions, and in which the white throat stands out. What I wonder is whether these are males, and whether females differ from males in having brown caps and ear coverts, (similar to the sex difference in Common Whitethroat).
This would make the bird I saw three days ago a female. I haven't seen it again as yet, (and I haven't seen a grey-capped bird either!).
The latest two issues of Birdwatch have included three photos of Ferruginous Duck, but I don't recall any recent ones of Lesser Whitethroat. It's not hard to see why, given the way the bird refuses to stay still in the open in the way its Common cousin (and Ferruginous Duck) often does. If photographers could get more spring photos of UK Lessers (before there are any juveniles to muddy the picture), maybe a sex difference will become apparent?