The recommended time for dividing these is spring - the problem this year is, although officially its spring, we're having high summer weather. The idea of doing it in 'spring' (March/early April) is based on the assumption that we're having cooler, damper conditions.

I agree I wanted to divide a few more plants yet but as the weather is like high summer I have given up for this year now.

Thank you Bamboo & Drc much answer much appriciated!