After much research, I have bought a de-bobbler. It has a large round head and a spinning disc inside, so that it cuts, not tears. A big waste compartment and either batteries or plugged in with a long cord. I used the plug
First try was on a thin woolovers jumper with stripes, including white stripes and it looked so tatty, the small bobbles were all over and the white looked grey. I was going to throw it out. Flat on the ironing board, very quick, easy and very satisfying with an excellent result. That jumper will be good for another season
Next try was on a textured hand knitted merino, heart in mouth for this one but again the result was excellent. I was very aware of the sharp blades so held it lightly
The waste compartment filled mostly with the woolovers stuff and some pink hm, I could see the cut bobbles clearly
Next step is inside out washing, then bagging carefully to store for next year
The de-bobbler that I settled on was called beautural and they have it on amazon but I had one brand new from ebay ( I never did renew prime)