I bought a set of NGK iridiums for mine for around £45.00 some time ago but when I came to fit them I only managed to remove one HT lead from one plug, even though they were replaced a few years ago and were lubricated with the grease provided with the lead set they are now firmly stuck to the plugs.
I didn’t want to risk tugging them so hard I damaged or broke the leads, if anyone has a safe removal method they could recommend I am all ears.