When Sunday’s Women’s FA Cup final assistant referee Sophie Dennington heard her phone pinging while she was in a strength and conditioning session, she was curious, but ignored it. Once finished, she saw three missed calls from her mum, Shelley, among the notifications and called straight away.

“She says: ‘Soph, I posted something on Facebook. All it is is a little grassroots page. I’ve seen loads of kids posting that they’re referees and they’re starting their GCSEs. Posts normally get three or four likes. All I wanted to do was just to post that you struggled with your GCSEs to show them that anything is possible and to just to keep going. I didn’t think it would get this many likes so quickly,’” says Dennington. She said goodbye, turned off her phone and went to work. After she had finished, she turned her phone on and saw the post and its 1.1 million views.

The message on the grassroots Facebook group said: “This is my daughter Sophie Dennington – I’m so proud of her. She started reffing at 15 years old. She struggled so much in school and at age 13 she had the reading and spelling age of a seven-year-old. With the help of her school, she managed to pass her GCSEs. She was diagnosed with dyslexia, but she still got her dream. She’s running the line for the FA Cup Women’s Final! A message to all the young refs out there. You can do it if you put your mind and heart into something!”

It was a lovely and inspiring message, but Dennington was in tears. “She put that [at 13] my spelling age and reading age was that of a seven-year-old,” she says. “I had a cry because I was embarrassed but then I started reading the replies and seeing how it was connecting with people and I thought: ‘Wow, OK, it’s not just me who went through that and it’s actually helping and supporting people.’ I had never seen it like that before. You forget to put yourself in other people’s shoes … I didn’t want to do any media, but I thought because it’s had such a positive impact and people have responded to it really well, I just wanted to come and say: ‘Yes, I did have a reading and spelling age of a seven-year-old, however I’ve got a degree now – it’s not stopped me.’”

Her school wrote her off before her dyslexia diagnosis, telling her not to bother looking at sixth-form colleges because she wouldn’t get the grades. “I took that and thought: ‘Who are you to tell me what I’m going to do with my life?’ I used that as my motivation. You’re not going to stop me from getting what I want. I couldn’t write half a page in English in years 8 and 9, but I wrote a 10,000-word dissertation and I was two marks off the first.”

Her diagnosis changed the way her family viewed her too. “I was diagnosed in year 8 and then it was like my family were like: ‘You’re not just lazy.’. My uncle would be: ‘Just read it out, just read it out.’ And I’m like: ‘I can’t because the words don’t match up with what’s going through my head.’ Then it was like: this is why my brain’s not working – I think my family felt a bit bad because they were trying to push me but they didn’t know how to support me in the correct way.”

Dennington will be at the Women’s FA Cup final for the second season in a row. Last year she was there as the reserve official. This year she will have flag in hand when Manchester United play Tottenham. It has been a breakthrough year, the 23-year-old one of five new officials from England to be added to the Fifa international list, as an assistant referee, for 2024.

Her refereeing journey began when she would banter with the referee of her school matches. “I was saying I could be a better referee than him. Because he’s older he wasn’t moving around the pitch much.” Her PE teacher thought she should give it a go but her mum couldn’t afford to pay for the course. “So my PE teacher had a word with my headteacher and he was like: ‘Look, I think we should pay for Sophie. Is there any budget?’ And my headteacher was like: ‘We’ll pay for her but she can repay us by refereeing the boys after school.’” The referee she would banter with became her mentor, offering advice and going to games.

When she got invited on a first international trip she had a big decision to make: whether to quit her job in Tesco, where she had been refused time off, and give up on ambition of becoming a police detective, working with people who have been sexually assaulted, because the training wouldn’t allow for the time off either.

“My dad was like: ‘Right, quit Tesco and you can defer the police. The police is always going to be there.’ … I haven’t looked back.”

Dennington becomes emotional when asked what message she would give her 13-year-old self – and the children watching her on the sidelines on Sunday.

“I would say: ‘Don’t be as hard on yourself.’ I’d go home and cry and I’d cry in lessons. I just didn’t understand why I wasn’t like everybody else. You’d look at other people and think: ‘Why am I not like that? Why am I struggling?’ I wasn’t good at anything. My escape was PE but I wasn’t great at it, I just felt free.

“As an individual you’re going to excel at something – you just need to find what you’re good at. And I think now my message would be to just stop comparing yourself to other people because you are your own person.”