The 20-year-old told her how thrilled he was to be making his first Scotland start and then to be named Man of the Match following the 0-0 draw.
The starlet’s family and friends revealed that Billy’s success was down to hard work, a roll and slice and even an ex-first minister.
His Nana Alison Clifford, 61, said: “He used to run rings around me with a ball when he was young and now he’s running rings around England players at Wembley.
“We were never in any doubt that he would make it to a high level. The whole family are football-daft and it’s always been a big part of our life.
“We weren’t able to travel to Wembley because of Covid restrictions but we watched it on TV. However, his mum and dad went down.
“I had tears of joy streaming down my cheeks when I saw him in his Scotland strip. It’s such a proud moment for our family.
“He called me on FaceTime to tell me all about it. He was so calm about it but said he was ‘buzzing’ about his first Scotland start. He’s like that – nothing fazes him.”
She said: “I’ve got four grandkids and Billy is the oldest but I still call him ‘my boy’.
“When his dad was in the Navy Billy and his mum and wee brother Harvey lived with me for two or three years. The boys were always out kicking a ball about.
“His mum and dad, who just live around the corner now, are super-proud, as you would expect.
“When they come back, we’ll celebrate but it won’t be big party – we’ll get a takeaway.
“Tuesday night [against Croatia] is a big game and we will all be going to Hampden together. Regardless of how excited we are, he’s very calm about it all.”
Billy grew up in the same town as most of his tight-knit family and called them all yesterday morning.
Auntie Sasha Pollock, 38, said: “It is incredible to think he wasn’t even born when Scotland last went to a major tournament.
“It’s been 23 years. We are super-proud but Billy isn’t some overnight success. He has trained extremely hard over the years.
“It’s been hard, hard work for him making it but he wanted it desperately. It’s all about dreaming big. If you dream big it can happen.
“He’s grown into a lovely lad and when he’s home, he’ll still come and see his wee cousins and play with them on the trampoline out the back.
“He’s just a normal 20-year-old and has made some real sacrifices over the years to become a footballer.”
Chelsea star Billy, who is teetotal, doesn’t even eat sweets but loves square sausage, known as “slice” in the seaside town.
Butcher Paul Barclay said: “They are a lovely family and come in regularly to get slice to send to him in London.
“I like to think it’s the secret of his success. It makes you proud when you see someone from Ardrossan on the world stage.”
Following the game, his mum Carrie, a nursery teacher, tweeted: “Absolutely delighted for you tonight. So so so proud of you. My heart is bursting with pride. Love you so much.”
Carrie regularly sends packages to Billy, who moved to London after signing for Chelsea, from Rangers, aged just 15.
Jo McMaster, manager of RS McColls in Ardrossan, said: “Carrie is in quite a bit getting packages to send to him in London.
“It must be hard when he’s so young. Everyone in Ardrossan is proud as punch.”
Billy was just 12 when he joined the SFA’s Performance School, brought in after a report into grassroots football by former first minister Henry McLeish in 2012.
His coach was ex-Partick Thistle and Dundee United striker James Grady, who said: “What you see with Billy is what you get. He’s a modest guy but has a steely determination.
“He is getting out what he has put in over the years. He was devoted and still is.”
McLeish, an ex-professional footballer, said: “I am over the moon about Billy’s performance – he showed great skill, energy, poise and maturity well beyond his very young years.”
Meanwhile, tennis star Andy Murray called Billy “my idol” on social media and Lorraine Kelly, who was at the game, said: “You are a fabulous fella.”
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