Stewart Robert Hinsley writes
I suspect that you would find that our approaches are not all that
different. (What I didn't mention was that after referring to Stace I
went to Google Image Search to confirm the appearance of the plant.)

So did I ;-)

My preferred references for identification at the moment are Garward
and Streeter (illustrations and field marks)

Is that the Collins one?

and Sterry (photographs, field marks and portable, but lacking
complete coverage).

Sterry I've seen but didn't like, but not sure why

In the case of Saxifraga cymbalaria, I don't think I have any works
which illustrate it.

It's illustrated in Fitter, Fitter and Blamey. That's the fat one, which
also covers grasses and ferns. It's drawings, which I like - Margaret
Blamey is quite good at getting all the key features, if you screw your
eyes up and peer closely (it helps to be short-sighted). And it has
distribution maps, which is a cheating way of narrowing down the search!

For photos, I've got some of the little books by Roger Philips, all
sadly out of print now and very hard to come by.

I can be wrong as well - working from the manuals only works if you
start in the right place.

:-)

That's my trouble with keys. I know the genus and can work straight from
the genus key I'm fine. But if I haven't a clue even as to family,
starting from the main key I find very tough.

And, I'm slowly training myself to identify plants in the field.

It is slow, isn't it? You can't go at it all at once (ie identify all
the flowers in the little patch of land you're standing on), as there's
too much to learn. For most things I'm confident only to genus level,
and am trying to extend it by looking at the weeds in our garden - spent
most of yesterday lunchtime peering at a forget-me-not with a hand lens.

--
Kay