I have a V Master card companion voucher and can't see whether it's limited to VS metal only or whether I can use it on delta, ANA etc.
VS metal only, as per the T&Cs:
4.4.8 Flying Club Upgrade Rewards, Companion Rewards and Complimentary Companion Rewards are not valid on codeshare flights. Applicable flights must have a “VS” prefix and be operated by Virgin Atlantic.
