Also to add to the confusion, Sarah Raven says, Early Large Flowered Group, Group 3 pruning ? I don't grow many of the large flowered clematis so I am only reading what is online. Apologies.
I don't quite understand this, but on the RHS site it says both Group 2 and Group 3 in the pruning section for Sally Evipo 077:
"Pruning Pruning (clematis) group 2, light prune for early flowers. Remove dead and damaged stems before growth begins in early spring. Trim all remaining stems to strong buds. Hard prune for easy-care option using Pruning (clematis) group 3"
Thank you @Plantminded I looked at the link for sally, and it says "Remove all top growth down to 6" (15cm) late winter/early Spring" which I suppose would be like Group 3 pruning then ...
Posts
https://www.thorncroftclematis.co.uk/clematis-sally-evipo077-8537-p
https://www.raymondevisonclematis.com/pages/simple-pruning
Details of Sally:
https://www.raymondevisonclematis.com/products/sally
Pruning (clematis) group 2, light prune for early flowers. Remove dead and damaged stems before growth begins in early spring. Trim all remaining stems to strong buds. Hard prune for easy-care option using Pruning (clematis) group 3"