Posing as a potential client and her friend, we had booked a 45-minute appointment with Mr Sawyer through his Instagram page. We told him we wanted a 200ml (7fl oz) liquid BBL injection costing £1,200. We paid a £200 deposit.

Despite having advertised that all liquid BBLs would be carried out under the guidance of an “ultrasound specialist doctor”, none was present at his pop-up clinic. He was working out of a small room in an east London office block – a non-clinical environment which would have increased the risk of infection.

Within five minutes of being in his office, Mr Sawyer had begun to encourage our reporter to think about increasing the amount of filler. “You might be surprised about how much product you can have and still look natural,” he suggested.

By the end of the appointment, Mr Sawyer had offered to inject a litre of filler – 500ml (almost a pint) per buttock – at a cost of £2,000.

We did not go through with it and later returned to put our allegations to him – but he refused to answer our questions and slammed the door on our reporter.

Reviewing our footage, plastic surgeon Dalvi Humzah, who sits on the Joint Committee of Cosmetic Practitioners, said Mr Sawyer’s actions were “shocking”, “very dangerous”, and putting patients at a huge risk of infection and potentially fatal complications.

“Putting that volume in, in one sitting, is really dangerous,” said Mr Humzah. “The buttocks are such a large area that if they become infected it can overwhelm the body and could end in sepsis – or even death.”