Sapper Walker's heartbroken mother paid tribute to her son, who was shot by a rogue member of the Afghan National Army.
Kathryn Walker recalled the moment she received a knock on the door of her home in Washington telling her of the death of the 23-year-old.
"He had just been here the week before Christmas.
"All he had talked about was getting back from his tour and spending time with his little girl.
"We'd arranged to have Christmas a week early so we could all spend it together. He was heading back to Camp Bastion on Christmas Eve.
"Even then, he felt so guilty about being away from the rest of the lads over there – he was devoted to them.
"He died doing what he loved best."
Spr Walker, of 28 Engineer Regiment, attached to 21 Engineer Regiment, died at Patrol Base Hazrat, in Helmand's Nahr-e Saraj district on Monday.
The gunman fired at Afghan troops and then Richard and his colleagues before being killed.
Spr Walker, whose daughter Lilly-Faith turns two in April, was briefly a pupil at Pennywell School in Sunderland before moving to Washington School.
His mother, who is being supported at her Blackfell home by other family members, said: "He'd wanted to be in the Army from being a little boy, it was all he ever talked about.
"He was such a lovely little lad, full of surprises, he loved going to school and got along with everyone."
Spr Walker had been a keen footballer and had played in goal for Washington Village, as well as being a staunch Sunderland fan.