The world’s most popular musicals have often been on the least likely of themes. Who would have thought TS Eliot’s poems or the founding fathers of the US would set the box office alight? The evidence suggests enterprising ideas can pay off. It is possible one such idea is the Covid-19 pandemic – certainly a story with an uncommon number of lows and plenty of potential for tragedy. But 2020 the Musical (★★), put together by the writer-director Natasha Mould and the composer Richard Vanryne, is a backstage musical – minus the stage – that reduces the most significant upheaval of modern times to a dreary tale of narcissistic musical theatre performers. Live entertainment was hit particularly hard by the successive lockdowns of 2020 and 2021. But this story about a couple of actors who are laid off, having only just landed parts in a West End show, comes across as indulgent. That they seem to blame their misfortune personally on Boris Johnson rather than, you know, the need to stay alive, adds to the production’s myopic worldview. It is as if the main thing about the pandemic was the way it hampered the cliched “dreams” of a couple of fame-hungry actors. To give the month-by-month plot a broader outlook, Mould reunites her redundant co-stars, Emily Goodhand (played by the playwright) and Adam Pictor (Tom Watson), in a care home where Emily is looking after Tom’s grandfather. It is a chance to remind us of the importance of the NHS during the pandemic and the pain of socially distanced bereavement, but the songs can’t help themselves veering off the subject to give us tap-dancing pensioners (let’s laugh at the old people!) and romance in the supermarket aisles. The young cast performs with gusto but the songs are laden with weak rhyming couplets (variants of “to,” “through” and “you” crop up a lot) and predictable girl-meets-boy emotions, despite there being no obvious reason for their mutual attraction. Equally self-regarding is I Wish My Life Were Like a Musical (★★★) by Alexander S Bermange who turns a satirical eye on that most pressing problem of the day: the injustices of musical theatre. If you thought it was about time someone exposed the villainy of auditions, the outrage of hitting the wrong note and the scandal of lead actors disliking each other, then this could be the musical revue for you. Finally, someone has blown the whistle on grandstanding divas. If you do not share these concerns, you may just think it a blinkered sendup of obvious targets, appealing to musical theatre obsessives with its insider references and pulling its punches at every turn. Directed by Matthew Parker, the show has on its side a well-written set of songs, the lyrics clear and concise, the melodies bold and accessible, as well as excellent four-part harmonies sung vigorously by this year’s lineup of Jennifer Caldwell, Rhidian Marc, Julie Yammanee and Sev Keoshgerian. Enjoying a third festival run, it has an enthusiastic following and meets with rapturous applause. There are more lyrically strong songs in Bed: The Musical (★★★), a collaboration between Tim Anfilogoff (words) and Alan Whittaker (music), working with the director Matthew Gould and musical director James Cleeve. It stars Madeleine MacMahon and Drew Elston as Alice and Ben who, across a through-composed hour, go from newlyweds to first-time parents of baby Jacob and onwards past extramarital affairs to gloomy news from the doctors. The conceit, such as it is, is that the whole story is played out in the bedroom, the actors hopping under the covers whether through lust, exhaustion or illness. It is a focused and economical idea that suits a small fringe stage, but is also limited in ambition. Dressed in beige, MacMahon and Elston give attractive performances of the succinctly plotted songs, but they play unremarkable characters whose experiences are too commonplace to generate much heat. Their excitement and doubts about cohabiting and bringing up a child are the same as anyone’s and the plot is low on surprises. Only because we have stuck with them through a lifetime do the closing songs have much poignancy. Curiously, the best of any of these musicals is made up on the spot. If you can’t wait until Hamilton arrives in Edinburgh in February, you can get in the mood with its freeform offshoot, Shamilton! The Improvised Hip Hop Musical (★★★★), making a return after its 2022 fringe debut. An extension of the Baby Wants Candy! improvisation franchise, it does not so much pay homage to the Lin-Manuel Miranda blockbuster, in the way the tongue-in-cheek Hamilton (Lewis) did five years ago, as borrow its hip-hop influences. You will know the format: the company solicits suggestions of famous names from the audience, hoping, perhaps, for a Hamilton-like historical figure, but settling for whatever pop-culture icon comes up. My audience cheered loudest for Lady Gaga, although the rejected candidates, Louis Theroux and Leon S Kennedy from the Resident Evil game, inspired some of the show’s more surreal twists. From there, the six-strong company – RJ Williams, Raquel Palmas, Will Naameh, Chris Grace, Derek Demkowicz and Kiki Mikkelsen on my performance, plus Adrien Pellerin on keyboard and Kenny Miller on drums – free-associate their way through an A Star Is Born-style story, using gentle hip-hop rhythms as a default, but merrily veering off in the direction of Beyoncé and Britney as the evolving saga demands. Only the most hardcore fan would be disappointed by the lack of Hamilton content, because they are brilliant at it. The cast are breezily adept not only at making up lyrics on the fly (naturally, there is a rap battle), but also at ad-libbing harmonies, backing vocals and basic choreography as the hilariously paint-by-numbers plot unfolds. 2020 the Musical is at Underbelly, Bristo Square, until 27 August. I Wish My Life Were Like a Musical is at Gilded Balloon at the Museum until 27 August and Wilton’s Music Hall, London, 29 August-9 September. Bed: The Musical is at Gilded Balloon Teviot until 28 August. Shamilton! The Improvised Hip Hop Musical is at Assembly George Square Studios until 27 August.