Lucas Grabeel was called "grandpa" on the set of 'High School Musical'

Speaking as part of a panel at MegaCon in Orlando, Florida, he said: "I always had some physical ailment or something and talking in Olde English slang, so everyone called me 'grandpa."

The 'Little Women' star appeared in all three films that made up the 'High School Musical' franchise as singer and dancer Ryan but initially auditioned for the part of basketball player Troy Bolton, a role that eventually propelled his co-star Zac to worldwide fame.

Former 'Suite Life' actress Ashley played Ryan's ambitious twin sister Sharpay Evans, and he admitted he was "p***** off" when he was paired for her because she was exactly like her character in that she would insist on running lines over and over again.

He said: "I met Ashley at the callback. We had originally had our normal audition ... then we had the callback and met with the director. We had originally had our normal audition ... then we had the callback and met with the director.

"That's when I auditioned for Troy. The director] was like, 'Oh Lucas, You are amazing but you are no Troy. But you are a Ryan.

"I was paired with Ashley and she really p***** me off.

"This girl. I mean, this is why she got the job - she was so Sharpay. She literally, we did the scene, we came out and she's like 'Hey, so I really wanna, like, rehearse and go over it again.

"And I was like, 'I'm kinda good, cause I did my homework and I'm ready to go.' And she's like 'No, please,' And I'm like, 'Okay, cool.' ... So we do the scene outside, by ourselves, and she's like 'Okay, so, when I say this line I want you to go over here and make this face. And then at this point, I'm gonna add this line and I want you to react to that.' And I'm like 'Whoa, she's giving me notes.

"I went to the callback and I had this, like 'Bro, be professional.' And that is exactly who Ryan is. He has this thing of like, 'I have to perform, she's driving me nuts, but I'll keep it all inside.' So thank you, Ashley for giving me notes."