If its only on the woody parts and not on the leaves, and you can reach, get yourself a packet of disposable cloths and a bottle of methylated spirits - moisten a cloth with the spirit (just damp, not dripping) and rub over the affected areas, scraping off the scale as you go. It's just one of the scale insects. You'll need the whole packet of cloths probably - they get really mucky and unpleasant, so wear gloves. Otherwise you'll have to use the dreaded Provado, which is dangerous for bees. If the bark's too rough to do that, dip a cotton bud in the meths and apply to each scale.

Thank you Bamboo....I am of to B & Q right now. I can't see any on the leaves. It seems to be centralised on the top of the trunk and where the main branches come out.
It's going to be tricky as this shrub is like a waterfall - but I need to try something. Thank you xx

This particular form of scale has been rife this year - and it doesn't usually affect the leaves, just the woody parts.

A quicker and more effective way is to soak crepe bandages in methylated spirits, bandage the trunk covering all the aphids then cover all the bandage over with clingfoil. This method is much quicker to apply and will not damage any bark formation. In a week or so you can take the whole thing off, burn it and check for any you may have missed.

Wow that is really good advice Dr B!

Thanks DrB....I've got the meths and the cloths, I will see how easily that goes, if not I will get my hands on some crepe bandages tomorrow and try your method.

Just thought I'd give you an update. Affected branches and trunk have been cleared.
I chose your method Bamboo as it was going to be easier than trying to wrap it all in bandages. It all came of fine and so far noohing has reappeared.
However, I still have the bandages to hand just in case!
Thanks Bamboo and DrB :)

Should be fine now, but check it again in Spring next year.