Ten years ago Richard Douglas Productions produced a gala concert at the Theatre Royal Drury Lane to celebrate Stephen Sondheim's 75th birthday. Ten years later almost to the day, they return to the same venue with a one-off gala to celebrate the esteemed American composer's 85th birthday, entitled Sondheim: Hey Old Friends. The 'old friends' element of the evening's title was doubly appropriate – not only is it the title of a song from Sondheim's cult flop Merrily We Roll Along, but with the Sondheim Society raising initial funds for the gala online via Kickstarter and many members present, it did feel like being in the company of a group of 'old friends'. If any uninitiated people had walked in off the street, they would have been going 'Into the Woods' in more ways than one. 

The most exciting part of a one-off event like this is the opportunity of seeing some top Sondheim practitioners all on one stage in one evening. Despite the withdrawal of some previously-announced artistes – Maria Friedman and Jenna Russell in their midst – Hey Old Friends staged a major coup by persuading Millicent Martin to fly over from her LA home to appear 'Side by Side' onstage with Julia McKenzie again. The years have not dimmed either's enthusiasm for Stephen Sondheim's work and they still have the old rapport. Although McKenzie was confined to a presenting role (which she does with panache), Martin brought considerable flair and irony to 'I Never Do Anything Twice'. Two time Sondheim Olivier Award winner Daniel Evans reprised songs from Sunday in the Park with George, where he was reunited and well-matched with his Donmar Merrily co-star Anna Francolini for a thrilling 'Move On/Sunday'. Evans is direct and sincere in his delivery, and Francolini's distinctive voice resonates beautifully. 

Sondheim's music is sometimes described as being elitist or inaccessible. It's certainly not to everyone's taste, so it was refreshing to open the gala with a pastiche song written and performed by Kit and McConnel, entitled 'People Who Like Sondheim'. The pair don the fun guise of a couple of Sondheim detractors who are chastised by McKenzie and Martin and forced to watch the show from the wings, reappearing as occasional presenters and eventually appearing in 'I Love Sondheim' T-shirts at the finale. Another cabaret-style act, Martin Milnes and Dominic Ferris, give a five-minute medley of almost forty Sondheim songs – an incredible feat of wordplay. Sondheim Society's Student Performer of the Year competition winners – much future talent in their midst – reunite for a group rendition of 'Old Friends', while experienced Rosemary Ashe and Laura Pitt-Pulford joined their considerable vocal forces for 'There's Always a Woman'. 

Some of the performers fare better than others with the often-featured lesser-known songs – Anita Harris brings a sense of longing and atmosphere to Evening Primrose's 'Take Me To The World', whereas Rula Lenska is less at home with 'Ah! But Underneath'. As always, the only problem with a gala of Sondheim music is what to include and what to leave out, as the material is such rich pickings. It's inevitable that some personal favourites are omitted – 'Ladies Who Lunch' from Company and 'Not While I'm Around' from Sweeney Todd among them. There aren't too many Sondheim showstoppers – that's not his style – but Bonnie Langford certainly stopped the show with 'Can That Boy Foxtrot!', featuring an acrobatic dance routine with Anton DuBeke and the male dancers. Leading up to the finale, the '11 o'clock Numbers' slot – appropriately enough at the end of the show – features some much-anticipated gems, including an earthy Tracie Bennett doing 'Broadway Baby' and a poignant 'Send in the Clowns' from Haydn Gwynne...Sondheim at his sultry best.