The midfielder was one of the stars as Rovers pulled off a cup shock by defeating Arsenal 1-0 at the Emirates to book their place in the quarter-finals of the FA Cup with a strong showing on his first outing.
"He wasn't one of the big name ones that have come in, but he's got a lot of quality," said the Rovers boss. "And I've got to say I thought he was magnificent on Saturday.
"From a composure point of view, in a first half where we lacked a little bit of composure at times when we won the ball back. He was the only one who I thought steadied the game down a little bit and played to his pace.
"I think a lot of players took that on board at half-time and when we won the ball back in the second half we were a lot more composed and played an extra pass when we needed to.
"So I was delighted with Lee, he'd not played for six weeks, he was a little bit sore and stiff yesterday as you could imagine, but he's going to be a good addition to the football club."
Williamson and Rovers are back in action this Tuesday night when they travel to the KC Stadium to take on Hull City.
Tickets will be on sale at the ground on the day of the game, cash only from the turnstiles. Prices are £25 for Adults, £15 for Seniors and 16-22s, Juniors aged 11-15 are £6 and it is £3 for Juniors aged 10 and under.
Call the ticket office on 0871 222 1444 for further information.