King Charles shared a laugh with Stella McCartney as they sat on the front row of a catwalk at London Fashion Week this afternoon – hours after Andrew Mountbatten-Windsor was arrested. 

The monarch appeared composed as he took his seat next to the British fashion designer, 54, before they entered into a conversation ahead of Tolu Coker’s show in central London today. 

At one point, Charles erupted into laughter as McCartney looked at him with a shocked and amused expression. 

It came just hours after the King’s younger brother Andrew was arrested on his 66th birthday and taken into custody amid a morning raid on his Norfolk home. The former Prince has since been released, with images of him being driven away at around 7.30pm on Thursday evening. 

Wood Farm on the Sandringham estate – the former Duke of York’s new house – was searched by Thames Valley Police along with his old mansion, Royal Lodge in Windsor. 

Multiple sources have claimed Charles and Buckingham Palace were not informed in advance of the operation by detectives. 

Yet Charles gave little emotion away this afternoon as he arrived on The Strand in London in his State Bentley, with large crowds gathering to greet him.

Two journalists shouted out questions for the monarch, asking: ‘Do you have any reaction to the arrest of your brother, Sir?’ and ‘Your Majesty, how are you feeling after your brother’s arrest? Have you spoken to your brother Your Majesty?’

Charles walked in without commenting and sat down for the show by British-Nigerian designer Coker, who was supported by his King’s Trust’s Enterprise Programme in 2018. 

Hours earlier, the King revealed the police will have his ‘wholehearted support and co-operation’, stating that ‘the law must take its course’. 

Calling for a ‘full, fair and proper process’, Charles added: ‘My family and I will continue in our duty and service to you all.’ 

Yet he still appeared to enjoy today’s show as he clapped along to the music and chatted to both McCartney and Weir, as models sashayed past.

At one point, the rapper Little Simz began to perform from her seat a couple of feet away from him before getting up to join the band at the centre of the space at 180 Studios in The Strand.

Charles earlier greeted McCartney with kisses as he toured her installation on sustainable British innovation. 

The designer was today unveiled as an Ambassador of The King’s Sustainable Markets Initiative and she showed him examples of sustainable materials she is using in her collections, including plant-based Ostrich feather alternatives, plastic-free sequins and a leather substitute made from mushrooms. 

McCartney presented Charles with a scarf and took control with organising a picture for a large group of media, telling the King ‘Let’s do a nice photo, ready, OK, come on, cheesy smile.’

When she realised the scarf needed to be rearranged, she said to the King: ‘OK, I’ll do this, let me organise this, here you go your majesty – ready, pull it’ and they both held the gift as they posed for the picture.

Many onlookers felt the monarch was making a firm point about his determination to continue serving his country while the legal process runs it course. 

Thames Valley Police arrested Andrew, the eighth in line to the British throne, on suspicion of misconduct in public office. 

The Daily Mail was the first to reveal plain-clothes police, carried in six unmarked vehicles, had arrived at Wood Farm, where Andrew now lives, at 8am this morning.

A convoy including at least two royal Land Rovers linked to Andrew was photographed leaving the estate less than an hour later. His arrest was confirmed at 10.08am.

For the past ten days detectives have been probing his conduct as a trade envoy for the UK after emails in the Epstein Files suggested he shared confidential information with his paedophile friend including reports of his official visits and potential investment opportunities.

A Thames Valley spokesman said today: ‘We have today arrested a man in his sixties from Norfolk on suspicion of misconduct in public office.’ 

The force said its officers are searching an address in Norfolk – believed to be Wood Farm where Andrew is exiled – and an address in Berkshire, likely to be Royal Lodge in Windsor, where he lived for more than 20 years until this month.

Norfolk Police said it is ‘supporting’ the Thames Valley investigation but did not say if one of its stations had been used by detectives to interview Andrew.

Thames Valley Assistant Chief Constable Oliver Wright said: ‘Following a thorough assessment, we have now opened an investigation into this allegation of misconduct in public office.

‘It is important that we protect the integrity and objectivity of our investigation as we work with our partners to investigate this alleged offence.

‘We understand the significant public interest in this case, and we will provide updates at the appropriate time.’