Writing a new musical, particularly one that boasts an original book, is no task for the faint-hearted. This three-hour hymn to the people who lived and worked in Tiger Bay, Cardiff, in the early 20th century is big, bold and hugely ambitious. It is as if everyone involved has sat around a table and decided: the only way is epic.
With music by Daf James and book and lyrics by Michael Williams, the show whizzes us back over a century to the docks where labourers known as donkey men haul their filthy loads, helped by ragged street children called water boys. At the drop of a hat everyone is ready to break into a song and dance à la Oliver!
But tensions are brewing. Hostility towards immigrants, particularly those from Africa, simmers beneath the surface. The brutal harbourmaster Seamus O’Rourke (Noel Sullivan, formerly of the pop group Hear’Say) is lining his own pockets while the Marquess of Bute (John Owen-Jones) is otherwise occupied trying to make contact with his dead mistress and child through a spiritualist.

Into the mix comes Themba (Dom Hartley-Harris), a man weighed down by his losses, who recognises O’Rourke as the guard in the Boer war concentration camp where his wife and child died. This is a show that is fond of symmetry, oozes melodrama and musical lushness, and seems to have taken Les Misérables as its template in more ways than one: jaunty water boy Ianto (Ruby Llewelyn) is cheeky chappie Gavroche in another guise.
Anna Fleische’s grey, monumental metal design suggests a castle and the might of industry dwarfing and crushing all human beings. Director Melly Still eschews the quiet invention of her 2005 show Coram Boy for full-on spectacle, with Max Barton as co-director. When the grieving Lord Bute announces, “It’s far too busy out there”, I found myself nodding in agreement. People leap about dancing even when they are just moving the scenery. After a while it becomes exhausting to watch.
There is passion aplenty, some impressive musical moments, heartfelt performances and, in the first half at least, narrative momentum. But Tiger Bay is also overlong, overstuffed and overblown. This is a throwback to the musical theatre of the 80s, not a signpost to the future.
• At Wales Millennium Centre, Cardiff, until 25 November. Box office: 029-2063 6464.