Peter Dejour - "Peter of the Day" - the 'duty St. Peter' - the receptionist on duty. This implies that the person waiting at the Pearly Gates, meeting the newly deceased and directing them to the appropriate afterlife, isn't specifically St. Peter. Rather more prosaically, it's a job shared by a number of people, and Ronnie meets the receptionist who happens to be on duty at the time. Maybe St. Peter only greets important people, further emphasising that Ronnie is no-one special. I feel that Dejour is one of the other souls in Limbo, an ex-mortal like Ronnie, rather than an angel. As discussed elsewhere, the angels of APP are remote, higher beings, and have no direct, spoken interaction with Ronnie.
In the Linwell production, this role was taken by Mark Ridley, aka Ian Anderson. Dejour isn't a key protagonist in The Play; his role is limited to that of observer and narrator. In Act Two, Scene One (The Memory Bank), the lines are in the second-person (i.e. 'you', so Ronnie can't be speaking them), but phrased as 'we'. I'd suggest that the person speaking (singing) these lines is Dejour, as spokesman (but not leader) for the assembled souls in the cinema. Other voices interject in places (e.g. the 'George' passage), but Dejour is the host and main narrator of the film of Ronnie's life - presenting without judging; a role Ian often plays in his songs.
Each band member is ascribed a part, but I suspect they're just intended as jokes:
The Projectionist: a non-speaking part, but essential in providing content, presumably at high volume. In the Linwell production, The Projectionist was played by Derek Small, aka Martin Barre....
G.Oddie might be expected to wear a white suit; the part was played by Ben Rossington, aka the famously white-suit-clad John Evan.
Magus Perdé: a shadowy figure in the background, but with tremendous influence over the eventual outcome - much like Barrie Barlow ('John Tetrad') on stage.
It's interesting that Ronnie is played by Jeffrey ('Max Quad'), as the first we hear of Ronnie is his failing heartbeat - played on Jeffrey's bass.
None of the band members is cast as Lucy (i.e. Lucifer) - that'd be too obviously playing into the hands of hostile critics! Imagine the headlines: "Ian Anderson is Satan!". Instead, the Linwell cast list has Lucy played by 'Ronald Pleasant', an obvious joke reference to the late Donald Pleasance, familiar in numerous gothic-horror films of the early Seventies.
Not so much of a joke, as it happens. Ian apparently told Yvonne Nicholson in 1974 that he wanted Donald Pleasance for the rôle of Lucifer in the aborted 'War Child' film project - so the Linwell cast list may have been something of a statement of intent!
The Angel was played by Lilly Schnaeffer.
All the characters listed in the Linwell Theatre cast list have clear roles in The Play, except one: G. Oddie Jnr, played by Lou Purcell. I suspect his inclusion in the cast list was merely for completeness, and primarily a joke for the theatre programme; Jesus has no direct part in the events described. If he was to be featured in the production, it'd probably be as a non-speaking observer in G. Oddie's office in Act Three, Scene Two.