In regards to unreleased material from his recent projects, Jeff confirmed that he remade enough classic ELO songs to issue a follow-up to the Mr. Blue Sky album, with I'm Alive mentioned as an outtake. He's also introduced Steppin' Out as a track that's since been reworked to his satisfaction, and while there's no way of being able to verify this until the new recording is available for comparison, I wouldn't be surprised if he relied on elements from the studio version when this was played at Hyde Park, as it's clear this approach was taken with quite a few other songs during that particular show (if not later ones as well, though I've yet to check these). Assuming this is the case, we can reasonably conclude that Jeff's also revisited All Over The World and Rock 'N' Roll Is King, plus it's heavily rumoured that he also tackled Don't Walk Away.
As for Long Wave, the "Down The Lane And Far Away" sampler disc proves there is enough leftover from this to create the majority of a similarly-themed sequel, and Jeff spoke of having several new compositions finished before he mostly started again with Alone In The Universe over the last year or so, with only When I Was A Boy dating from the earlier sessions. Going back to just after the release of Zoom, we know that One Day was intended for an album that ultimately failed to materialise, plus it's claimed that Point Of No Return was included on Mr. Blue Sky despite originally being meant for yet another project. Also, let's not forget that Cold Feet was salvaged from the aborted second record under Jeff's contact with Reprise, proving that Zoom didn't entirely evolve out of this as once believed by many fans.
There's really no way of knowing just how much could theoretically be dusted off from inside Jeff's vaults to produce new albums, as he's supposedly been recording intermittently for years. Until the announcement of such tracks as Surrender and Latitude 88 North, we had no idea these existed at all, with the usually teasing Rob Caiger never speaking of there being any incomplete ideas Jeff could polish up for release. Only a handful of demos have so far made their way out, and we know that a home recording of It's Over very nearly made it onto Flashback. Speaking of that compilation, who could have known there were four further outtakes beyond the previously documented Secret Messages casualties until these arrived out of the blue, to use a very apt pun?
Additionally, higher quality sources for the so-called Trojan Tapes Sessions that were released by Nathan James a while back are also in the hands of a lucky collector who bought those CDR acetates pressed at Abbey Road to audition potential bonus tracks for the remastering campaign, with the mythical Supersonic at least confirmed to exist in an alternate form with Jeff providing lead vocals. I realise this is never going to be legitimately approved by Jeff due to his perfectionist nature, but here's a look at what could be put together using just the home demos or unreleased studio material from the original ELO period we know he's sitting on:
Open Your Eyes (from Trojan Tapes Sessions)
Auntie (Ma-Ma-Ma Belle demo, from March 1973 tape)
Bev's Trouser's No. 7 (Showdown demo, from March 1973 tape)
Theme From A Glass Table (Daybreaker demo, from March 1973 tape)
Terd Behrgeler (Everyone's Born To Die demo, from March 1973 tape)
Unknown #1 (demo, from March 1973 tape)
Unknown #2 (demo, from March 1973 tape)
Indian Queen (full demo, recorded 19/09/1974 for Sight And Sound)
The First Days Of September
Billy The Ballerina (supposed working title for an Eldorado era outtake)
O So Lonely (AKA Like A Rat Up A Drain, from Trojan Tapes Sessions)
Give Me Fever (AKA Black As A N****r's A**e, from Trojan Tapes Sessions)
Surrender (original 1976 demo)
Supersonic (from Trojan Tapes Sessions)
It's Over (home demo, very nearly released on Flashback)
Latitude 88 North (original 1977 demo)
Poor Little Fool (full demo, recorded 1978 for Helen Reddy)
All Over The World (full band demo, recorded late 1978)
I'm Alive (full demo)
The Fall (full demo)
Xanadu (full demo)
Xanadu Overture (later reworked into Love Changes All)
The Way Life's Meant To Be (different versions recorded at several studios)
Time (album test acetate with different tracklist and possible alternate mixes)
Sad Affair (described by engineer as an outtake from the Time sessions)
Danger Ahead (home demo, confirmed to exist by Richard Tandy)
Hello My Old Friend (home demo, confirmed to exist by Richard Tandy)
Beatles Forever (Secret Messages double album mix)
Beatles Forever (alternate acetate version, supposedly slower with an extra verse)
After All (Secret Messages double album edit)
Danger Ahead (alternate early acetate mix)
"The Garden Rehearsals" (confirmed to exist by Rob Caiger)
Ballbuster (completed as Grieg's Piano Concerto In A Minor and included on Flashback)
Who's That? (later completed and included on Flashback)
Tears In Your Life (original vocoder version, reworked and included on Flashback)
Helpless (later completed and included on Flashback)
Balance Of Power (album before remixing took place between mid 1985 and early '86)
Heaven Only Knows (unedited alternate version)
Calling America (alternate versions from CDR acetate)
Is that pretty much a complete list of what we know to be out there? On top of all these, there's also the long-rumoured Time Tour recordings, which either come from the US or European leg depending on the source. What I can be sure of is that in addition to at least one concert being filmed, Jeff reviewed tapes from this tour for a potential highlights disc meant to have formed half of a double album, abandoning this plan due to some as-yet-unknown technical issue that led to him writing enough songs for Secret Messages to have been purely a 2xLP set of studio tracks... If only he'd throw open the vault door!