Anyway we can reduce our Swiss family health insurance which costs circa CHF 1,100 per month: Being English and Swiss, do Bupa or someone similar do a Global annual policy which we could use instead, whilst still being being officially resident in Zurich ?

Short answer, No
Longer answer, Swiss law requires you to be insured with recognised insurer if you are resident here. BUPA probably wouldn't offer you a suitable policy and even if they did it would probably not be cheaper than anything offered here for the same cover.

thx. with the current GBP/CHF exchange rate, Swiss Health Insurance is just crazily expensive at over CHF 1,000 per month for a family of 5, its close to GBP 10,000 per year

While I agree that health insurance is a serious blow to our budget here, when you moved you passed to a Swiss salary, so comparing with GBP doesn't make much sense...

Increase your deductibles.

Tom

You need to stop trying to compare pounds and Swiss Francs. You live in Switzerland now so comparisons for this sort of thing are a waste of time. Have you checked on Comparis.ch to see if you can find anything cheaper?