The Manchester City manager, Nick Cushing, pressed the importance of blooding youth after three of his charges – 22-year-old Keira Walsh, 20-year-old Georgia Stanway and 18-year-old Lauren Hemp – scored the goals in a ruthless second half that undid a battling West Ham in the FA Cup final.

“We have to expose our younger players to these occasions because we want them to reach their potential,” said Cushing. “Regardless of the result we had to get Lauren Hemp on the pitch, just as we had to get Georgia Stanway on in 2017.

“Of course, it helps when you’re in control of the game but you have to expose these players because they are the next Nikita Parris, Jill Scott or Steph Houghton.”

Manchester City beat West Ham 3-0 to win Women's FA Cup final – live! Read more

City – denied the Super League title by Arsenal despite being unbeaten with one game to play – completed a domestic cup double in front of an overwhelmingly hostile crowd at Wembley by clinching their second FA Cup, beating opponents making their first appearance in the final.

The Hammers, who turned professional only last summer, took the game to the Women’s Super League runners-up in the first half. But a mistake from the West Ham goalkeeper Anna Moorhouse, who took a step the wrong way as Walsh struck from 25 yards, meant they were chasing the game and forced to leave gaps at the back. These were duly exploited by Stanway and Hemp as the clock ticked down and West Ham legs got heavy.

As the game kicked off with the crowd clearly behind West Ham, despite the clash with the men’s fixture, and “Come on you Irons” ringing round the stadium, the players in claret were making their presence known to a frustrated City.

With Stanway – who shared a photo of her younger self queuing for a photo with her now teammate Houghton at the 2013 final in the buildup to this match – kept quiet, outmuscled by a steely Hammers back line, Parris was City’s greater weapon in the first 45. Fed the ball on the edge of the area, she took a touch, looked for an opening, but a West Ham defender dived in front of her shot.

Facebook Twitter Pinterest Steph Houghton holds the trophy aloft. Photograph: Jonny Weeks/The Observer

With half an hour gone, West Ham had the best chance of the first period. Erin Simon’s whipped cross from the right was steered beautifully between the City centre-backs and Jane Ross’s downward header was goalbound but Karen Bardsley made a superb save to push the effort wide of the post.

Cushing described the save as “huge” and added: “So was the save she made in the Continental Cup, so were all the penalty saves. I can look back to KB making a save against Kelly Smith in my fifth game against Arsenal. She’s made huge saves and continues to make huge saves.

“I think in these big games myself, and England fans, see the value of KB in that goal, she’s so big and I think she thrives off making those big saves. We’re all going to say Walsh and Stanway were excellent but KB has probably impacted the game more than anybody by keeping it 0-0.”

After the break an irritated City looked to regain the momentum. The previously quiet Stanway then burst to life, taking advantage of a rare break to square to Walsh in the middle but her shot was watched past the post by Moorhouse.

Walsh was not about to make the same mistake twice, though, and with 52 minutes gone she danced past Kate Longhurst and her 25-yard shot bounced past the terribly wrong-footed keeper.

Looking to turn the screw, City flooded forward again but it was not until the 80th minute that they found their second. Stanway swerved past Brooke Hendrix and Gilly Flaherty with ease before powering a low shot inside Moorhouse’s far post.

“I don’t think you ever imagine it because some things you just don’t think are possible,” said Stanway. “But today I’ve just gone one better and achieved dreams that go beyond people’s imagination.

Facebook Twitter Pinterest City celebrate the first goal scored by Keira Walsh. Photograph: Jonny Weeks/The Observer

“That picture [of her and Houghton] proves how important role models are. I’ve always looked up to Steph. It was unbelievable, I remember queuing for a good half-hour to get that picture with her but she’s one of my best mates now so she’ll give me stick for how my hair looked.

“I think sometimes you get caught up in the bubble of matches and training and you forget what’s on the outside. Today makes it worthwhile. If we inspire 10 girls we’ve done our job but hopefully today we inspire thousands.”

The icing on the cake was added by Hemp with almost her first touch after coming on, and Moorhouse was again at fault. She raced out of her box and the stranded keeper was punished by the 18-year-old who fired past her into the empty net. It was a cruel end to the West Ham fairytale.