Robert Walker was a goalie who was in the squad photo in 1938/39.
From the Supporters Club Handbook 

"ROBERT WALKER, signed during the close season. Walker is ideally built for the position, and more. over he is a 'keeper who has had con siderable experience. First coming into prominence with Falkirk and Motherwell, Scottish League clubs, he sampled Continental football last season, which he spent at Malta. With all his travels, Walker must not be regarded as anyway approaching the veteran stage."

The following is courtesy  "motherWELLnet" 

"Twenty year old reserve goalkeeper, Bobby Walker broke into ‘Well top team in season 1933/34. He was back up to Alan McClory and Jock Robertson, both of whom picked up injuries throughout the campaign. Alan suffered from ligament damage in the early part and Jock suffered a horrific cut to his hand in a game against St Johnstone. Young Bobby would feature in the next three games for the club in a hectic three day period. Firstly in a New Year’s Day derby against Hamilton Accies at Fir Park which was won 2-1, secondly a 3-1 victory over Falkirk at Brockville and then his third and final appearance of the season was a 1-2 defeat at the hands of Queen of the South."