It hardly needs stating that the musical landscape would be very different without Rough Trade. Tonight the label celebrates its forty years of existence with a unique show at the Barbican Centre, a venue with a level of prestige they could only have dreamed about in 1976.

This is the opening night of a series of anniversary events, and clearly a lot of effort has gone into making this particular show a one-off; there are three sets, each combining a ‘legendary’ Rough Trade act with a newer or more leftfield stablemate, along with a number of talks and films on both the history and the future of the label.

Opening the musical proceedings are 70s post-punk noise merchants The Pop Group joined by relative newbies Protomartyr. Perhaps reflecting the genesis of their label, the set is a bit rough and ready, but as they warm up there is real, raw energy pouring from the stage and discordant, bleakly industrial noise.

Scritti Politti make the kind of noise perhaps more suited to this luxuriously-upholstered venue, and with the light-touch contribution of Alexis Taylor, augmenting the vocals or crouched over a xylophone, it’s a beautifully arranged set – the pearl of which is a cover of Chic’s ‘At Last I Am Free’ which sees Taylor and Green Gartside combine for some multi-layered falsetto loveliness. There is genuine warmth between the musicians at the culmination of their set, and a real sense of occasion.

For John Grant’s headline set with electronica supergroup Wrangler, the stage is set up like a boardroom of electronica, the top table of electronic noise, a straight black-shrouded bench behind which stand the four musicians and a multitude of offbeat black boxes. In a small dark room, with a standing crowd, the intensity and discordance of this set would be pretty special.

Sadly, this intensity dissipates in the wide open spaces of the Barbican, leaving us with something quite sterile. Grant’s impressive presence will always draw the eye but as the audience come to realise, this is a long way from a conventional John Grant gig. The atmosphere takes a dip, which is a real shame – it’s a unique performance, but doesn’t quite hit the mark.

That said, tonight’s event is proof – if any were needed – that Rough Trade’s adventurous spirit, forward-thinking attitude and determination to do things just a little bit differently means the label will continue to shape the musical landscape.