Some very good fares here ex Zurich with Swiss, so will need a positioning flight. Same fares are also available ex Geneva. Bangkok in business for £1,350 or £ 2,700 in First for example. I’ve not checked how they compare with other carriers but for Swiss they’re very good.
All prices shown are in Swiss Francs with a current roe of 1.48 to the £ but they are non changeable, non refundable.