Back in the day when my OH got a bonus in shares from BA, which is admittedly a long while back as they have not done it for ordinary employees recently, the shares were put in trust for 3 years and could not be sold during that period. If that applies to Mr Walsh's share bonus, that could be described as 'deferred'.
If that is the position, and he did forgo it as stated in the article, then it's gone permanently. How £550,000 share bonus got to be £1.1 million (ie double) in the headline, don't know, unless he is to get the bonus for two years under his remuneration package. At any event, he appears to have given up the first share bonus, and the year before's cash bonus, time will tell whether he takes the second share bonus if that's what he is due.