Walker has signed permanently for Colchester this week.
Drummy told chelseafc.com: "I'd like to wish Sam all the best. He was in our Youth Cup-winning side and he's been an exemplary young professional for me. He's a very well-mannered lad and Mark Beeney [Academy goalkeeping coach] has done some great work with him. Sometimes you need to take one step back to take two steps forward and I've no doubt Sam can go on to play at a higher level in the future."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball