For the first time in Boris Johnson’s ignominious history of calling in planning applications for steroidal slabs of luxury flats, and readily giving them the BoJo rubber stamp, comes a scheme that has proved too much even for the London mayor’s own advisers to stomach.

Their 131-page planning report (pdf) on proposals for the Bishopsgate Goodsyard site concludes that erecting 12 buildings of up to 46 storeys, forming a gargantuan cliff face on the edge of a conservation area, “would result in unacceptable and avoidable significant negative impacts”. Full marks for observation.

The mayor will decide the fate of the scheme next week, in a one-man planning committee reminiscent of an imperial court. Of the 14 controversial applications he has presided over during his reign, he has never gone against the advice of his planning team. Although they have always recommended that permission be granted, until now.

The project has been one of the most fiercely opposed developments in recent history, provoking a petition of 11,000 signatures and 500 letters of opposition, along with 150 local businesses, local MPs and the local planning authorities of Hackney and Tower Hamlets forming a united front against it. In an unprecedented campaign, Hackney council placed advertising at bus stops warning of “a dark future for Shoreditch” and detailing the development’s effects as the “Destruction of local creative and tech community”, “Shadow cast across homes and businesses” and “Unaffordable £1m+ flats not the homes we need.”

It was an unexpectedly ferocious response from the two boroughs, given they had both happily waved through several other towers in the immediate vicinity that could have been accused of these evils.

Principal Place across the road to the west in Shoreditch is a Norman Foster scheme for an office building (which will house Amazon’s new HQ) and a 50-storey golden apartment tower, described by developers as “a new global icon”, where flats halfway up the building are on the market for £3m. Just 13% of units will be classed as “affordable” (ie, up to 80% of market rent) – the borough’s target is 50%.

One block to the north, hoardings surround the site of The Stage, a 40-storey tower of “luxurious apartments with a Shakespearean twist”, the twist being it is on the site of of one of London’s earliest theatres, where Romeo and Juliet was probably first performed. “Sorry,” says the hoarding, apologising not for its ungainly heft, but because all the flats are now sold, bought off-plan long ago by investors. Hackney gladly waived the requirement for any affordable housing in the scheme because of the great burden on the developer of preserving the archaeology, allowing 40 “affordable” homes to be built off-site instead.

Across the road, where Chariots gay sauna and a Majestic wine warehouse still cling on, will soon arrive the lumpy 30-storey tower of the Highgate Hotel, designed by the global corporate firm Gensler in what they say “evokes the raw factory-style of the former industrial Shoreditch”. Did someone forget to tell them factories don’t usually take the form of big glass towers?

Then a little further down the street, right next door to the Goodsyard site, already looms the graceless bulk of the optimistically named Avant Garde tower, the tallest of any of the completed Shoreditch towers so far, but a mere sapling at 25 storeys. The work of Stock Woolstencroft, east London’s go-to architects for fast-buck developers, its own marketing material boasts that it will “dominate the skyline”. Shortlisted for the Carbuncle Cup, its gaudy chequerboard of cheap green glass and metallic beige panels will soon be drowned out by neighbours with much bigger ambitions.

It’s not hard to see why Hammerson and the Ballymore Group, the big-gun developers behind the Goodsyard, are a bit peeved. They’ve been trying to nurture their own £800m thicket of luxury towers since acquiring the site from Network Rail in 2002, and now everyone else has beaten them to it – using the Bishopsgate plans to justify their own aspirational stumps. Hackney’s planning guidance, published in 2009 (pdf), says the Goodsyard is a site for “a tall building opportunity area with scope for a prominent building” and suggests 2,000 homes could be built there, indicating a density a good deal higher than the 1,356 units being proposed.

A closer look at the scheme reveals an equation that simply doesn’t stack up; an attempt to throw a slice of Manhattan at a site incapable of supporting it. Most of the towers are to be built on top of the giant concrete box that houses Shoreditch High Street overground station, meaning they start from a position that’s already 26 metres in the air. The rest of the site is taken up with the mainline railway from Liverpool Street, an eight-track reserve for Network Rail, the protected Victorian Braithwaite viaduct, the Central line and BT Tunnel running underground, as well as strategic views that criss-cross the site, limiting the location of tall buildings.

It’s a series of constraints that made the developers think they could get away with providing zero affordable housing, later offering 10% as a gesture of “goodwill”. The GLA planners are now insisting on 25% affordable units, plus a payment of £21m for more off-site homes. If the mayor refuses the scheme, they will no doubt be back with buildings of a lower height but increased bulk, a different kind of stubby wall to blight Shoreditch.

A more welcome fate would be to take down the hoardings and open up the crumbling viaduct as east London’s own feral version of New York’s High Line; a ruined memorial to the developers who proposed too much – even for Boris.