Yes provided you make sure the relevant FF nos. are included in the record - not an easy task sometimes with BA. Note reduced AA mileage/point earning benefits (25%) in most BA economy classes; however WT+ is a good 1.5 q-point earner (as is J of course.) So if you did LHR-DEL-LHR in WT+ or above, that would be enough for the Plat challenge.