Ran a few search terms on this thread but to no avail so sorry if already clearly answered somewhere I've missed.
My question as a UK resident and cardholder is: can you use an Amex companion voucher to book a return trip starting from USA to UK and return back to USA?

The Wiki states:
[Legacy Vouchers Only] Valid towards return flights only, with the journey originating from and returning to your country of membership (with the exception of vouchers issued in the UK which may also be used for one-way travel)

So I think this means yes but it's not clear.