Longstaff was on the scoresheet and said: "There was some really good stuff in there, they started really well. Under the cosh for first 15 minutes but the first goal settled it down and from there you saw our attacking players take over the game.
"When we're really aggressive and running forward we are a really good team. It's been there in fits and starts this season, but a really good day and something to build on.
"We've got the luxury, when everyone is fit, of some elite forward players. Alex (Isak) scored, Will (Callum Wilson) scored and Jacob (Murphy) was chipping in with assists. When we are fully fit and you bring Miggy (Almiron), Joelinton, Harvey Barnes on, it's a top squad. Unfortunately for us it hasn't been like that all season.
"I'm happy to score. Me and Jacob and Tino (Livramento) have a good relationship off the pitch. Jacob played a lovely pass and I just had to get good contact. It was a good end to the first half and you can see when we are in full flow we are a really dangerous team."
On Newcastle's fans, he added: "They follow us up and down the country and there's days where unfortunately for us we've not been there, so it's good to give them away day to remember - there's nothing better."