Dr Asim Shahmalak, consultant hair transplant surgeon at Crown Clinic, is one of the UK's leading expert on hair loss.
His celebrity clients include Coronation Street star Jack P Shepherd, TV doctor Christian Jessen, model Calum Best and Homes Under The Hammer presenter Martin Roberts. He gets media enquiries from all over the world. The subject he is asked about most often at present is Prince Harry's hair loss.
Specifically, people want to know why the 35-year-old royal is losing his hair so quickly. Here are some of the most popular questions.
How quickly has Harry lost his hair since marrying Meghan and becoming a father compared to before marrying her – and why would that be?
Dr Asim Shahmalak said: "Prince Harry's hair loss has accelerated in the last two years since his marriage to Meghan.
"Over that time his bald patch has more than doubled in size. His bald patch is most noticeable around the crown area but his hair is thinning fast towards the front of his hairline, too.
"While stress is a small factor in hair loss, the main reason for his hair loss is the Windsor baldness gene.
"Prince Harry has just been unlucky. That gene has really kicked in just at the time that he has met the woman of his dreams. His hair loss was much slower before he met Meghan. I don't think meeting Meghan is a factor. His baldness gene took off at exactly the wrong time."
How does Harry’s hair loss compare to his brother and dad’s hair loss?
Dr Asim Shahmalak said: "Prince Harry is now experiencing the aggressive hair loss that his older brother William went through in his 20s. William is 37 now, two years older than Harry, but he pretty much lost all the hair on the top of his scalp in his 20s. By the end of his 20s, Prince William was balder than his father (Prince Charles) and his grandfather (Prince Philip).
"Prince Harry's hair loss was slower to take root than his older brother. They have the same baldness gene but it does not always proceed at the same rate amongst family members.
"Harry's hair loss has really accelerated in the last two years. He will be as bald as his big brother if he does not take action.
"Prince William has chosen to embrace his hair loss, wear his remaining hair short and do nothing about it. I suspect that Prince Harry will be more proactive in sorting out his problem.
"It was reported earlier this month that Prince Harry has been seeing a trichologist about using hair thickener products.
"There are clinically proven drugs you can take to combat hair loss.
"Finasteride, also known as Propecia, could slow down or even stop Harry's hair loss.
"A lot of men take in combination with a hair transplant. It won't grow him any new hair but it is clinically proven to treat hair loss and is effective.
"A very small number of patients experience symptoms such as loss of libido and the growth of man boobs. These might put Harry off but they soon go away when you stop taking the drug."
What are the causes of hair loss usually?
Dr Asim Shahmalak said: "The overwhelming cause of hair loss is your genes. It started with Prince Philip and has now been passed down to Prince Charles and on to his sons Prince William and Prince Harry. Let's hope baby Archie doesn't get it, too!
"It is a myth that the baldness gene is only passed down on the mother's side. Even here, there is a pattern of hair loss because Harry's mother Princess Diana had a bald father in Earl Spencer.
"So Harry has the baldness gene in both sides of his family. He was always at a high risk of suffering male pattern baldness."
What reasons do most men who come in to have hair transplants give for their choice to have it? Could Meghan have persuaded him to go and get a hair transplant?
Dr Asim Shahmalak said: "Prince Harry could have come under pressure from his bride Meghan to tackle his hair loss.
"She was a Hollywood actress in her former career so she knows very well the value of looking good.
"A lot of my clients come due to subtle pressure applied by their partners who would rather not be dating a bald man. That could well be what is happening with Harry.
"It is important to stress that Prince Harry has not had a hair transplant at this stage. He may well be taking medication to slow or halt his hair loss but it is very difficult to hide having a hair transplant when you are as high profile as Harry. You would have be able to tell through the scarring in the immediate aftermath of the operation.
"But the only way that Prince Harry can properly tackle his aggressive hair loss is with a hair transplant. He is at a good age and at a good stage of his hair loss for such an operation. He still has a good covering of donor hair at the back and side of his scalp and a hair transplant operation could make a real difference to his appearance, making him appear years younger.
"If Meghan isn't already persuading him to have a hair transplant, she should do.
"It is too late for Prince William. His male pattern baldness is at such an advanced stage that there is little that can be done to cover it up, short of wearing a wig.
"That is not the case with Harry. His situation can still be salvaged but he needs to have a hair transplant in the next couple of years to stop the rot and also take medication to slow down or halt his hair loss. There is no reason why Harry should eventually be as bald as his brother, father and grandfather if he takes action now.
"Prince Harry is about to embark on a new career away from the royal family where he will need to be attractive and marketable to big brands. A good way to do that is with a hair transplant.
"I would not be surprised if Meghan was advising him to have one. And that would be very good advice.
"Harry could have a FUE (follicular unit extraction) hair transplant like my clients Jack P Shepherd and Calum Best
"Hairs are extracted individually from the back and sides of the scalp and replanted in the balding areas on the top.
"With 1,500 grafts, which amounts to around 3,000 individual hairs, he could fill in his bald patches. He may need a further hair transplant a few years later if he does not take medication to slow down his natural hair loss. But there is every indication that he is already taking that medication."