Described as “a policeman through and through”, he died saving the lives of motorists by directing them away from the crumbling Northside Bridge in Workington when it suddenly gave way beneath him at 4.40am on Friday.
His widow Hazel, 44, led the tributes to Pc Barker, saying: "How do you put into words how you feel about somebody you are so proud of? Bill was my best friend, my forever friend and an amazing dad.
"Even when he was exhausted from work he would always take time out for the kids. I have the comfort of knowing Bill died doing the job he loved and the fact he was helping others is typical of Bill."
Gordon Brown, the Prime Minister, described Pc Barker as a "very heroic, very brave man", adding: "I think we owe him a tremendous debt of gratitude for the service he has shown."
Pc Barker, of Egremont, had served with Cumbria Police for 25 years and leaves four children, Simon, 16, Melissa, 15, Daniel, 13, and Emma, six.
His body was found on a beach in Allonby several hours after he disappeared from the road bridge.
Craig Mackey, Cumbria’s chief constable, said: “Bill was a wonderful police officer and a real family man. He was due to celebrate his 45th birthday tomorrow.
“He was directing motorists safely off Northside Bridge, saving lives, when the tragic incident occurred.
“Bill was a wonderful police officer and a real family man. He is a hero who died saving the lives of others and our thoughts are with his family at this devastating time.
“He was a much loved friend, colleague and an inspiration to everyone he knew - he will be sadly missed.
“His friends say he loved being a police officer and, a passionate biker, he was part of the constabulary's dedicated roads policing unit. He was a sterling officer and had won a number of awards throughout his 25 year service.”
Nicola Patterson, 24, one of his neighbours, said: “Bill was a nice fellow. He was a policeman through and through, one hundred per cent. He gave everything for his job and what he was doing on the bridge was very brave."
Sir Hugh Orde, president of the Association of Chief Police Officers, said: "Being part of the police service means walking towards danger and, in the best traditions of the service, that is what Bill Barker bravely did.
"All within the police family will be greatly saddened to hear of his death."