Russia’s president Vladimir Putin could not have written it better himself. “There is a call from some oppositionists for nationwide street demonstrations tomorrow that almost certainly will not be authorised,” the email stated. “Please make sure you stay away from public areas of gathering around 2pm tomorrow and please refrain entirely from making related posts in any media.”

But it was not sent by his police chiefs, Kremlin propagandists, or the security services. It came from the Moscow office of McKinsey, the management consultancy.

“In line with policy, McKinsey employees must not support any political activity either publicly or privately,” wrote Russia managing partner Vitaly Klintsov in a note to staff on Friday. “This ban does include posts in social media featuring your political views or your attitude to any action with a political flavour. This line of conduct is mandatory,” he added, under the subject line: “Stay safe, stay neutral, enjoy weekend.”

The Saturday demonstrations were called by Alexei Navalny, Russia’s best-known opposition activist and Mr Putin’s most prominent critic. He was arrested and jailed last week on his return to Russia from Germany, where he had been recovering after surviving an assassination attempt using a Soviet-developed nerve agent in August. The EU, US and UK have demanded his release, while the European Court of Human Rights has ruled that the conviction used against him was politically motivated.

Sitting in his cell, facing a potential 13 and a half years behind bars, Mr Navalny would probably scoff at Mr Klintsov’s use of the word “neutral”.

Mr Putin likes neutrality. After 21 years in office, he sits atop a regime that revolves around people not making a positive choice. It does not rely upon support, only an absence of those willing to oppose. And those oppositionists, as Mr Klintsov adroitly states, “will not be authorised”.

To adhere to political neutrality in Mr Putin’s Russia is to embrace the status quo, and accept that those who have built the authoritarian model of government are the only ones with the power to alter it.

This is almost codified into law. Mr Navalny is barred from running in a presidential election against Mr Putin, and rules adopted last year make it hard for anyone affiliated with him to stand. New restrictions on online content could now be used to block his popular YouTube channel, which this week racked up more than 90m views for a video investigating an opulent mansion allegedly built for Mr Putin on the Black Sea.

Protest is the only real option available to Mr Navalny, and any other would-be challenger to Mr Putin. The Kremlin’s priority is to stop people attending.

A day after Mr Navalny called for the protests, Mr Putin’s spokesman warned that they would be illegal. Police squads rounded up and arrested prominent opposition activists days in advance of the rallies. And the country’s communications watchdog ordered social media services to remove posts referring to planned locations and times.

Universities across the country threatened to punish or expel students who attended the protests, with one college warning students that alumni who joined previous anti-Kremlin marches “encountered difficulties in finding jobs”.

Set against this, Vladimir Kara-Murza, a Russian opposition activist, described McKinsey's email as “shameful”. US senator Marco Rubio, noting the firm’s work for Russian state-controlled companies, said it “raises serious questions about McKinsey's core values” in a letter to the firm’s global managing partner.

In a public statement, the company said: “McKinsey supports its employees’ rights to participate legally and in a personal capacity in civic and political activities across the countries we operate. The recognition of these rights is unqualified.”

On the day of the protests, tens of thousands of people took to the streets of Moscow, St Petersburg and over 100 other cities in Russia. More than 3,700 were arrested and thousands beaten by truncheon-wielding riot police. Further protests have been called for this weekend. Mr Navalny’s fate may depend on how many people show up. Mr Putin will be hoping they instead remain neutral.