What is a "Companion Voucher"?

becominganobsessivesaver

I love travelling in business (don't we all) but am restricted to school holidays and we're a family of four. My companion voucher has been used for a trip to jfk and back from cancun next summer (out first back business) but I could only get availability for two of us. We've booked the other 2 cash CW tickets. With the sale and a BA hotline fare they've cost under £2500, so cash cost for the four of us is £3700 including the card fee. In total I see this as fairly reasonable (ish)!!!! We'll have used 110,000 avios and will get about 26,000 back.