From a new analysis of latest household projections against completion rates by Civitas
They dont include backlog, or areas where there is likely to be a shift in migration from job growth/decline in certain areas.
those areas that are expected to grow most rapidly over the next 25 years are, on the whole, already performing least well against their household formation projections. As can be seen at a glance from Map 1, housing supply is failing to keep up with household growth most in London and the South-East, where affordability pressures are already most acute. Measured in this way, there are also considerable supply issues in the North West and West Midlands, two areas that are the focus of concerted regional growth strategies for the years ahead….
The 30 fastest-growing non-London local authority areas in percentage terms are almost all in the South-East Of those, 21 were below the national average in terms of their housing supply measured against household growth, and only five supplied enough homes to keep up with long-term need….
To some extent, under-supply in fast-growing areas is made up by ‘over-supply’ in neighbouring or nearby ones; this is a key element in the ‘duty to cooperate’ in the National Planning Policy Framework, that asks local authorities to work together to manage housing supply across boundaries. Oxford, for example, met only 66 per cent of its household growth in 2015/16, but output in the surrounding districts compensates for this so that, for Oxfordshire as a whole, housing supply was 159 per cent of long-term household growth. Brighton and Hove supplied enough homes to meet only 56 per cent of its long-term growth, while West Sussex partly made up for this by supplying 113 per cent of its growth….
Frequently, however, even this is not the case as we have seen already in London. As can be seen in Map 1, there are broad swathes of the South-East where the under-supply of new homes is not balanced out by an ‘over-supply’ in nearby locations. This is also true in other strategically-important parts of the country. In the North-West, Greater Manchester (Bury, Manchester, Oldham, Rochdale, Salford, Stockport, Tameside, Trafford and Wigan) collectively supplied only 68 per cent of long-term household growth. The West Midlands (Birmingham, Coventry, Dudley, Sandwell, Solihull, Walsall and Wolverhampton) collectively supplied 71 per cent. Both Greater Manchester and the West Midlands are themselves surrounded by areas of higher housing supply – which is much less true of London and large parts of the South-East. [They could also have mentioned Bristol here and Cambridge]
This report is essential – if the figures were recast to include backlog and a nationally balanced addition to reflect job based migration (Natantial Licthfield im looking at you) then we essentially have a mapped definition of where the regional planning problem is. Correlate the problem with Green Belt and the availability of browlfield supply from NLUD and you have a map of shortfalls the Housing White Paper will need to make up.
Decisions, Decisions, Decisions 
This report is of course very limited in its analysis and therefore needs to be treated with extreme care. It takes no account of actual supply, planning permissions yet to be built, large strategic sites coming through the system and other factors such as the on-going housing recession in many parts of the county. It takes very naively one year’s worth of net completions, what the housing industry actually felt it worth to build or could sell. Using the previous year or next year would produce completely different results. We need more reasoned and well though out research rather than simple sound bites…which on further examination are pretty spurious.
Not relevent as no national dataset is available for this data. If concerned about year on year use moving average. Permission based data even more unreliable.