As soon as he emerged from his coma Alexey Navalny, the Russian opposition leader apparently poisoned by novichok nerve agent, expressed his determination to return to Moscow. But what future is there for an anti-Putin political movement in a country where dissent is all too often seriously bad for your health? Stephen Sackur speaks to Leonid Volkov, opposition politician and chief of staff to Mr Navalny. Is there any weakening of the Kremlin’s grip on power?