Thomas Harrison and Simon Hewitt were a few months old when each sustained permanently disabling injuries whilst being cared for in 1989 by Mrs Christine Walton, 36, Mr Justice Scott Baker said.
The medical evidence pointed overwhelmingly to the fact that Thomas' injuries were caused by 'severe shaking' and the cause of Simon's injuries were 'either a direct blow to the head or severe shaking', said the judge.
The childminder was found to have been responsible for the injuries although her husband, who had also been accused, was absolved of all blame.
Surrey was also found liable after the judge ruled its child minding officer Peter Bodycomb had failed to tell Mrs Dowling the full circumstances of Simon's injuries sustained shortly before Thomas was placed with Mrs Walton.
Had Mrs Dowling known the full facts behind Simon's injury she would never have entrusted Thomas to Mrs Walton's care, said the judge.
Mrs Walton was legally aided throughout most of the trial and the court heard it is 'realistic' that Mrs Dowling will first of all seek damages from the County Council.
The amount of compensation has yet to be assessed and may be the subject of a further High Court trial.
Both Mrs Walton and the county were ordered to pay the legal costs of the trial which began in July last year.
But the judge ruled that Surrey should be allowed to recover 90% of whatever damages and costs it is ordered to pay from Mrs Walton.