Bannigan and Thistle team-mate Stephen O'Donnell have both been included in Billy Stark's squad for Wednesday's friendly against Greece in Korinthos.
The pair caught the eye of Stark after an impressive run of results by the Irn-Bru First Division side and Bannigan acknowledged McNamara's role in their success.
The midfielder said: "He was the one who played us every week and got Thistle playing some not bad football. It's mostly down to him, although the players on the park are doing it as well."
The phone call that broke the news of the call-up came from McNamara, who quit Firhill to take over at Dundee United last week.
Bannigan added: "It was unexpected. I got a phonecall last Sunday night just saying it was a possibility and to be aware of it.
"I wasn't taking it for granted until it was official. I then found out for certain on the Monday.
"It was a good feeling. I've never had this before at any level.
"There is a wee bit of apprehension but I'm just delighted and looking forward to it.
"I'm a First Division player but they obviously recognise we are doing not a bad job at Partick Thistle."