His name is unknown, but resonates like that of a character from Astérix the Gaul. Jean Castex is France’s new prime minister, with a government reshuffle to follow. In ridding himself of the stolid and popular Edouard Philippe, Emmanuel Macron is playing his last hand in the presidential poker game to reset his troubled presidency.

In fact Macron has appointed Edouard Philippe’s double. Castex, like his predecessor when first appointed to Matignon is unknown among the public, but an enarque, technocrat, top civil servant, member of the conservative Parti Républicain, with a foot in local mayoralty. A small difference between the two is Castex’s down-to-earth southern accent, something unheard among prime ministers of the 5th Republic, albeit dominant in the 19th century.

Macron has chosen Castex precisely because he is unknown and unlikely to cast a shadow across his route to the 2022 presidentials, unlike Edouard Philippe. All because Macron wants to take back control for his last ‘500 days’. In the purest constitutional tradition of the 5th Republic, Macron will take the big decisions and Castex daily management. And Castex ticks all the right boxes; a top civil servant, yet mayor of a small town in the south of France; able to work Parisian corridors of power, yet in contact with local affairs and opinion; someone deemed to have successfully organised France’s lockdown exit while at the same time uniting France’s disparate sporting organisations in preparation for France’s organisation of the 2023 Rugby World Cup and 2024 Olympics.

In short, Castex – ‘the swiss knife’ – has a reputation for knowing how to piece together the near and the far, but also most importantly the baroque and disparate Parisian ministries in a way that Dominic Cummings seeks for Whitehall.

But for all Castex’s qualities, his association with former conservative president Nicolas Sarkozy – whose deputy chief of staff he was at the Elysée, and whose trial for fraud begins in October – could provide fodder for his political detractors.

In choosing another prime minister clearly of the right Macron is hoping to draw even more electoral support from his natural right-wing supporters. ‘At the same time’ (en même temps) – to coin Macron’s notorious phrase – the Elysée will try to balance this political bias through the government reshuffle likely to be completed by Monday.

Following Macron’s party drubbing in the municipal elections last weekend that saw LREM win no major city while the greens picked up a host from Lyon to Strasbourg, Macron’s watchword is ecology. He will attempt to tap into the green vote in the reshuffle, perhaps with a beefed up environment ministry, or even by linking it with the powerful agriculture ministry or even that of economics.

Macron in his last television broadcast to the French last month underlined his intention to re-invent himself while pursuing his original reforms. But whatever Macron might do to attempt to maintain the pretence since 2017 that he is ‘neither right nor left’, the appointment of Jean Castex firmly casts him in with the former. That may be a mistake when it comes to the presidentials where he will be up against Marine Le Pen and in need of centre and left wing votes to get through to the second round.

There is also the problem of Edouard Philippe who now becomes a loose canon. Given his national popularity – with 60 per cent of the French wishing him to remain prime minister – Macron has set up a potential rival for 2022. Macron today hoped to blunt Philippe’s ambitions by inviting him to unite the disparate forces of the presidential majority in preparation for the presidentials. This attempt to keep him in the political tent is risky. For Edouard Philippe could so endear himself to Macron’s majority and his old party, Les Républicains, that he becomes their champion for 2022.

For all his grand strategic manoeuvring Emmanuel Macron never misses an opportunity to drop a clanger that comes to haunt him. This was the case with his occasional condescending throwaway lines mocking members of the public.

This morning when the Elysée’s attention should have been on the reshuffle, Macron gave a newspaper interview stating that although he was going to reinvent himself he would still bring back to the table his very unpopular pension reform. Immediately trades unions were on the war-path claiming that this was ‘pouring oil on the fire’ when France should be concentrating on protecting jobs and restoring the economy in the worst recession since the Second World War.

Autumn was already going to be volcanic in terms of labour unrest. But re-opening the pension wound on the day of the appointment of the new prime minister is unhelpful, to say the least. The enormity of the task facing France economically and socially is enough of a programme in itself. The question is now whether Macron and his refreshed government will be up to the task. That is by no means certain.