Time was when it was almost axiomatic that a new concerto would be premièred by its composer, pretty well from the beginnings of the genre until the onset of the recording age, which captured Rachmaninov at the keyboard for his own concertos. These days, though Rachmaninov is barely 60 years dead, composers and performers inhabit such separate boxes that it's a surprise to see a composer step forward to perform his own piece – the more so when the composer is a violist; the last person to do that may well have been Hindemith. So when Brett Dean came to the front of the Barbican platform on 15 April, to join the BBC Symphony Orchestra under the baton of Ramon Gumba, he became an important link in a fairly short chain.