It’s 50 years this month since the Soviet Union abruptly ended the Prague Spring. On August 21, 1968 Alexander Dubček’s newly introduced liberal regime with a free press, no travel restrictions and a partially decentralised economy was brought crashing down. By coincidence, just hours after Russian tanks rolled into the then Czechoslovak capital, the USSR State Symphony Orchestra took to the stage at the Proms. Evgeny Svetlanov conducted a programme that included a Czech masterwork, Dvořák’s Cello Concerto, played by Mstislav Rostropovich.