Brown scale?

You're doing about the only thing that can be done, as far as I know there's no chemical treatment for scale; doesn't usually kill the plant though, even if it is infested. I must say, I've never seen scale as large as that, so perhaps it's something else...

a soapy spray will upset them a bit and cause them to dry out. they have a bizarre life cycle. the female lays eggs and then when the little ones hatch they eat the female. yuk.

Growing success winter wash, according to the rhs info sheet. There are different species and some can be 1cm in length.

These were only a few mm in length.
Thanks guys.

Just to add to the above, to prevent any damage to trees, shrubs etc. infected by scale or wooly aphids, methylated spirits applied with a small artist paint brush is a complete kill and destroys any infection brought in by these pests.

Thanks Doctorbob, that's useful to know!

Thanks Drbob