Who are the people involved in the Downing Street cronyism row? The key figures explained

There are so many strands to the current cronyism allegations engulfing Downing Street that it can be difficult to keep track.

Here's a quick guide to some of the lesser-known key figures whose names have been mentioned in the course of the story.

James Dyson

An industrialist and the UK's richest person with an estimated net worth of £16.2 billion, Sir James now finds himself at the centre of a row about who gets privileged access to government. Messages published this week show the prime minister agreeing to "fix" concerns the businessman had over his employees' tax bills as they worked making ventilators. Though a longstanding supporter of Brexit, the businessman's vacuum cleaner company Dyson has announced it is moving its head office to Singapore.

Dominic Cummings

A former chief of the Vote Leave campaign and then the prime minister's chief advisor, Cummings is a controversial figure. The government expended plenty of political capital over the summer defending him after he famously broke lockdown rules by driving to Barnard Castle – only for him to leave the government a few months later amid a row over who had the PM's ear. Was accused of leaking the Dyson text messages, but denied it, and then a number of accusations of his own – including that Boris Johnson had suggested using donor money for luxury refurbishment of No.10.

Henry Newman

A government advisor with close links to Michael Gove, Newman is accused by Mr Cummings of being behind previous government leaks - including one last year on plans for a second Covid-19 lockdown. A close friend of the prime minister's fiancé Carrie Symonds, it is alleged by Mr Cummings that the PM talked of calling off an inquiry so that he would not have to sack Mr Newman.

Carrie Symonds

Despite not having a formal position in the government the prime minister's fiancé reportedly has his ear on political matters – and is supposedly responsible for changes in his presentation such as a smarter haircut. A power struggle between aides close to Symonds and aides close to Cummings apparently led to the latter's departure last year. Symonds works for a conservation charity, and previously worked at Conservative party central office, a job she reportedly left after questions were raised about expenses claims she had made.

Lex Greensill

An Australian banker who founded the financial institution Greensill Capital, Lex Greensill enjoyed a close relationship with David Cameron while the latter was prime minister – claiming to be a senior advisor to the PM with an office in Downing Street. At one point a billionaire who operated several private jets, the businessman in turn enlisted David Cameron's own services to lobby the government on his behalf. It was the revelations that Mr Cameron had approached the chancellor Rishi Sunak that turned Westminster's attention to the question of cronyism and access to ministers.

Simon Case

The Cabinet Secretary is head of the civil service has has been in the job since September last year. Mr Case is said to have been personally involved in internal correspondence about the Downing Street refurbishment – which has raised eyebrows among opposition politicians and Labour says was "strange and misplaced". The youngest cabinet secretary ever, Mr Case, 42, will be quizzed on Monday by MPs on the public administration select committee.