[Spencer]

As I understand it, they typically voice track slightly ahead of schedule, dropping the links into the running order as they go along. So what you’re hearing was probably only recorded a few minutes beforehand, allowing them to respond to listeners’ messages and anything topical that’s going on.

I did the same from our spare room when doing a bit of cover on my former colleagues’ new station about a year ago. It was quite handy being able to get about half an hour ahead of schedule at one point so I could take the dog out for a quick walk.

That sounds likely, after all they'd want some listener interaction (I haven't listened to hear what sort of thing they do) . He said he normally prepares 40mins to an hour for a 2 hour show and you can VT a 2 hour show in 20 mins, but he didn't say what sort of VT is done for Boom. 

Presumably the inability to do it live is down to Internet bandwidth?

The system I was using, Myriad, had the capability for live remote broadcasting, although it seemed rather more complicated and less foolproof than the voicetracking option.

It might just be that when the presenters don’t have any technical help on hand, they’ve decided to keep it as simple as possible, particularly when the presenters are of a generation that maybe less au fait with digital systems.