After falling behind inside the first minute, the visitors fought back to claim a point in Essex.
The hosts were ahead inside the first two minutes. After making progress down the right, a cross came all the way across to former Town loanee, Jacob Murphy, who tapped home from close range at the far post.
The winger would cause Swindon problems down the left flank on a number of occasions but the home side were unable to capitalise on the chances they created.
At the other end, Nathan Byrne’s cross just evaded Andy Williams before the full-back tested Walker in the United goal and Ben Gladwin lifted a free-kick over the bar.
In first half stoppage time, Walker produced a superb save to keep out Williams, throwing himself to his right to paw the volley behind.
Just eight minutes into the second half, it was Gladwin who drew the Town level. After Andy Williams’ shot had been blocked behind for a corner, Gladwin met the resultant set-piece with a near-post header that came across Walker. The ‘keeper got a hand on the effort but couldn’t keep it from going over the line.
It was then Town’s turn to create chances: Jon Obika and Massimo Luongo were both denied by Walker before substitute, Jermaine Hylton created a glorious chance all by himself but could only poke his effort wide.
At the other end, the home side struck the post shortly after a sweeping move down the flank had ended with George Moncur slicing an effort wide.
It was Walker who had the final say, however: firstly, he did brilliantly to keep out Jordan Turnbull and Rapha Branco before diving at the feet of Jon Obika to smother the ball.