Dina Asher-Smith's former PE teacher at her Orpington school says she was a "humble" student when she competed in sports days.

The 23-year-old produced a dominant run to win the 200 metres world title in Doha on Wednesday night, breaking her own British record with a time of 21.88 seconds.

Asher-Smith also won a silver in the 100m on Sunday, and will now be targeting more sprint glory at the Olympic Games in Tokyo next summer.

Teachers and students at her old high school, Newstead Wood, could not have been happier for her.

"I remember asking for her signature when she was in Year 9, saying 'you will definitely win an Olympic medal', and I still have that which is really nice," her PE teacher Arlette Meader told the PA news agency.

"One of my best moments though was sports day. I started the 200m race and bless her, she'd finished before the rest of the children had got to the 100m mark.

"You just knew from an early stage how good she was. But she never made anything of it, she was very humble with it, she would encourage everybody else.

"She'd have got to the finish line and then be cheering everyone else on, and that's the kind of person she is."

Head teacher Alan Blount admitted Asher-Smith's exploits had captured the imagination of everyone connected to the school - even those not currently in the country.

"Last night I was being texted videos from Berlin where we have a school trip. Our head of history who is out there, who taught her, the students, they're all following her," he said.

"Teachers are texting each other in the evenings, we can see the children on Twitter are liking and posting, so we're all behind her, it's great."

Abigail Smith, a Year 10 student at the school, was hugely impressed by Asher-Smith.

"I wasn't surprised to be honest. She absolutely dominated the field, she put her heart in it and came out with the gold," she said.

Holly Lewis from Year 9 added: "She's got a really great determination, so when she puts her mind to something she really goes for it and you can see that when she's racing."

Glynnis Agyampong from Year 9 sprinted home from an evening Latin class to catch up on what went on.

"I was bugging my dad, asking 'is it on the TV (yet)? Has she won?'," she said.

"When I found out I was really excited and happy for her."