Nigel Simms (Con), then chairman of Harrogate BC's area planning committee, should have declared an interest and left a meeting but instead stayed and used his casting vote to give friend and fellow councillor Margaret Atkinson (Con) outline planning permission in breach of six material planning policies.
The councillors could give no valid planning reasons for their decisions.
Local Government Ombudsman Anne Seex said Mr Simms 'had a clear prejudicial interest and, by failing to acknowledge and declare it he breached the Code of Practice'.
She concluded Mr Simms' involvement was 'maladministration leading to injustice'.
Ms Seex recommended the council 'should consider what action it should take to cancel the planning permission which was improperly obtained'.
And she said the council 'should review the training it currently offers to members to clarify any areas of doubt surrounding personal friendships'.
A statement from the council said: 'All councillors serving on the planning committee currently have to go through compulsory training (repeated annually) before they can serve on the committee.'
It added: 'The planning training for members will be strengthened in the light of this complaint.'
Read the report here
Policy & Politics
Housing, Planning & Environment