By 2030, 1.5m extra people – almost as many as currently live in Birmingham – will be added to the 8.5m living in London now, according a report called ‘Growing London’, commissioned for Mayor Boris Johnson and published on Friday.

The first of a series of reports called the ‘Good Growth Agenda’ written by the Mayor’s Design Advisory Group, it examines what London will look like as it develops to accommodate a population of 10 million-plus.

London has already surpassed its previous peak of 8.61m people back in 1939, but whereas in the Thirties more than 500,000 houses were built on greenfield land, now the emphasis is on planning to increase housing mainly within London’s footprint.

The report says that around 50,000 new homes will have to be built every year over a 20-year period to house nearly 70,000 people in London and the equivalent of more than eight Canary Wharfs to provide jobs.

One of the key findings of ‘Growing London’ was the need to re-think London’s overall density – which could mean building more tower blocks. It points out that Londoners live at a density of 73 people per hectare, whereas 200 years ago there were 297 – more than four times as many people per hectare. It points out that if London had the same density today as in 1815, its current footprint could accommodate nearly 35 million people.

Density levels vary across London with a peak of 271 people per hectare. But this is relatively spacious when compared with the 585 people per hectare in New York and 1,111 in Hong Kong.

Another way to measure density is to count the number of units or dwellings per hectare. A density of 450 units per hectare would be usual for a tower block.

But the report says that while guidance suggests that there should be an upper limit of 405 units per hectare, some developments in London – it doesn’t say where – have been proposed hitting densities of more than 3,000 units a hectare, and that more research needs to go into understanding the challenges of higher-density building.

Currently, 263 buildings that are 20 storeys tall are in the pipeline for London.

Other key points to emerge from the report were that local authorities have almost stopped building new homes – despite owning 40% of land that could be used for housing. Whereas in the mid-sixties and seventies local councils built about three-quarters of all new homes, in 2014/2015 only around 310 of the 26,843 new homes were built by local councils.

The report also suggests that at least 154,000 homes could be built within existing town centres, which already have good transport links, shops and offices, with the potential for up to 218,000 homes within 10 years. It also says there is some opportunity for building low-density areas of outer London that have good transport links, creating a new generation of ‘Metro-lands’.

Recognising that the public needs to be more engaged with the planning process, it says information is often “lost in translation” when it comes to public consultations – and that an “A4 site notice and an online planning database” are inadequate to communicate the key characteristics of a planning application.