The pair claimed they had told the boy's mother, Francesca Brock-Hollinshead, to go straight to hospital after she attended an antenatal clinic for a check complaining of stomach pains, but she had refused. Mrs Brock-Hollinshead denied she was given this advice and returned home while she was in labour.
Her son Oscar, now aged six, was born at home several hours later in a "traumatic" breech delivery during which his head became stuck and he suffered brain damage due to asphyxia. The judge, who found the health authority liable yesterday, said Oscar would need care for the rest of his life and is expected to award Mrs Brock-Hollinshead a sum in excess of pounds 1m.
John Crowley QC, sitting as a deputy judge, said he preferred the evidence of the mother, and that notes made by the consultant and midwife about their advice were added after the home birth went wrong.
Mrs Brock-Hollinshead was booked for the birth at Farnborough hospital, Kent and was seen by consultant obstetrician Dr Edgar Tatford at the Masons antenatal clinic on 19 March 1991. The judge said that he was "driven to the conclusion" that Dr Tatford, consultant for the Bromley group of hospitals in Kent, had added notes to his original after the birth to give the impression that he had advised the mother to go straight to hospital.
Mr Crowley said: "I appreciate that this is a strong finding to make against someone of his status but having heard the witnesses and considered the relevant documents, that is my finding."
The judge said that two entries in the medical notes made by Sister Ruth Coull, that the mother was to be admitted to hospital and that she appeared to be having contractions when leaving the clinic but had refused to go to hospital, had been made at different times.
He said: "As her cross-examination proceeded Sister Coull conceded that the entries she had made relating to events in the corridor were unfair to the mother. It then emerged that the entries had been made ... after the disaster of Oscar's birth had occurred."
Mrs Brock-Hollinshead, 33, now of Cranleigh, Surrey, was eventually seen by an obstetric team at her home when Oscar was delivered up to his neck and there was a delay of five to 10 minutes in freeing the head.
The judge said that it was Mr Tatford himself who had first used the word "disaster" to describe the circumstances of Oscar's birth.
He added: "I am satisfied that he could and should have taken steps to discuss the matter properly with the mother and explain to her what had gone wrong. I find that the reason why he did not do this or indicate in any way to the hospital authorities that there was at least cause for further inquiry is that he had been at fault on the 19 March 1991 in not advising the mother to go straight to the labour ward."