OK, this is where I ended up.
Swiss pricing is a ripoff :-) I'm not totally sure if it is "personal", or whether native swiss people get the same outrageous rates. Some sites I found suggest that expats in many countries are charged more for life insurance, but that might be because:

most sites/companies offering "international" (life) insurance, or even catering specifically and "exclusively" for brits abroad in Europe / Suisse appear to charge nearly as much as the local swiss companies I tried. Well, why try harder, I guess? Some companies attempted to explain this huge discrepancy, but werent very convincing ;-)

Eventually, I had a breakthrough - calling Legal and General DIRECTLY, not through an agent, they said they would offer me more or less UK rates, on the following conditions:
1) I am a UK national
2) I have a UK "family" address. My parents were OK
3) the premiums are paid from UK bank account by direct debit
4) At the time of taking out the policy, I intend to return to being a UK resident at some point in the future. There didnt seem to be any specific timescale they required, so I said something that seemed reasonable to me given schooling etc.