In a video on a website launched by Calderdale Council to entice more film crews to the borough, Emma Jane Richards says they needed a square for their show - and The Piece Hall fitted the bill perfectly.
"Our scout was very fortunately on Twitter and an event came up in The Piece Hall and she said 'Have you seen this place?' and I was like 'No, I've never seen it, and I've been to Halifax. I've been to an amazing gig at the Minster and it's literally down the road and I've never even gone inside The Piece Hall - didn't even know it was here'.
"It's a fantastic place. Julia, our location scout, called up The Piece Hall and they said they would entertain the conversation, which was quite interesting because the conversation is would you be willing to let us bring a huge film crew? Is there a way we can bring something like 400 people into Halifax, all the associated vehicles, all the associated technical equipment, and the road closures and the parking and everything that comes with that?
"And they were like 'Yeah, why not? Come and have a chat'."
She said the support of local authorities is essential for productions like Secret Invasion.
"There is absolutely no way this project would have happened without the full support and engagement of everybody at Calderdale Council. That is a huge part of why this has been such a success," she said.
And she added: "I love it when you bring a crew and they all get involved with the local community and the local shops. I think it's just a lovely place to be.
"I can't get over how friendly Halifax has been. People are curious and interested but it's always very friendly and we try to always be friendly as well so we've had a lovely time.
"I think Halifax is such a friendly place. It feels very much like a community."
She also said the people she'd met in the town had been keen to share details about the area, and had helped find other filming locations for the series.
"I wouldn't have found Dean Clough if it hadn't been for a conversation with a local," she said.
"I wouldn't have found some of the streets at the back of Halifax that Calderdale Council closed for us if I hadn't had chats with some local people.
"The thing about Halifax and Calderdale is there's been such a spirit of welcome. The doors have been open wide for us.
"I brought as many of the scenes that we could shoot as I could possibly could because I knew that Calderdale could deliver it.
"I absolutely would bring a production back to Halifax."
Crews descended on the town in January, filming at The Piece Hall and Dean Clough as well as Bull Green in Halifax town centre.
Hollywood megastar Samuel L Jackson was spotted, along with Emilia Clarke, Cobie Smulders, Ben Mendelsohn and Kingsley Ben-Adir.