Thanks, Justin. I've never known what it was. It was given to me as a cutting, years ago... It's very vigorous. It's gone under some weed suppressing menu for about 2 yards, and is going up the back fence too. Plants go their own way sometimes, don't they?
Well, the poor old clematis has had a severe pruning! It was growing on an arch that was floored by Storm Katie. The whole lot fell into the pond. Ouch! Archway gone, clematis had haircut, new plan needed!