Kathy Carpenter, senior planning officer at Braintree District Council, was speaking yesterday at Planning's National Planning Summit, in a session on the government's new standard method of assessing housing need.
The standard method was introduced in last year's revised National Planning Policy Framework (NPPF) and aims to simplify and standardise the way housing need is calculated by local authorities.
Carpenter said: "We welcome the principle of the standard methodology but a big problem is the confusion around the implementation of it and the instability."
She went on to say: "Looking at appeal decisions, frankly, you have got inspectors not knowing what they're doing sometimes.
"I don't think they should be doing appeals on housing land supply unless they can pass a test that proves they know what they're doing, like a driving test with the standard methodology. Because they're supposed to know better than us."
Carpenter gave the example of a recent appeal in which, she claims, an inspector concluded that the council could not demonstrate a five-year housing land supply but they based their calculations on pre-NPPF methodology.
She also criticised the government for updating housing need data twice a year, which she said "complicates things".
She said: "It would be so much better if it changed just once a year rather than change in the spring with affordability ratios and then change again in the autumn with the hosing delivery test."
Also speaking in the same session was Derek Stebbing, a consultant with Intelligent Plans and Examinations and a member of the Local Plan Expert Group that first proposed introducing a standard method of assessing housing need.
He said: "I totally accept that this twice a year business is not helpful. There should be synchronisation of the data to get it at least get it to an annual basis."
Under old planning guidance on housing need, authorities were advised to take account of economic growth forecasts when calculating how many homes to plan for in their area. But this factor has been dropped from the standard method.
Stebbing told the session: "The economic growth uplift applied to [objectively-assessed need] was in many cases pure fantasy, based on political aspirations for economic growth that in many places never will happen."
Andrew Lowe, a senior planner in consultancy Turley's economics team, said he disagreed with that assessment: "That's an easy view to take from a southern perspective, that a lot of housing is demographically-driven.
"But in the north and midlands, housing is a really critical infrastructure to support economic growth in the future.
"I think planning should have some aspiration."