>>> his ex wife re married so a decree absolute was definitely obtained
That's not necessarily true. It's not unknown for people to enter into a second marriage by simply 'forgetting' their first marriage and filling in the paperwork as if they've always been single. It's illegal (and almost certainly invalidates the second marriage) but it certainly does happen.
Who actually applied for the decree absolute? (It's not issued automatically after a decree nisi. If neither person applied for it, it won't exist).