The letter to communities secretary Eric Pickles is signed by Johnson, the British Property Federation, the Planning Officers' Society and business lobby group London First and calls for the exemptions to the rules, which allow offices to be converted into homes without the need for planning permission, to remain in place for key London business locations.
The Department for Communities and Local Government (DCLG) has just finished consulting on plans to make the office-to-residential PD rights, which were temporarily introduced last May for three years, permanent.
It is also proposing to remove the exemptions granted for 33 areas of the country, including much of central London and Canary Wharf, that were granted when the rules came into force.
Exemptions were granted where councils had demonstrated that rules would lead to the loss of a "nationally significant area" of economic activity or "substantial adverse economic consequences" at the local authority level.
But the DCLG’s consultation said the exemptions would not be carried over when an amended, permanent PD right is introduced in May 2016.
The letter states: "We are in agreement that the current exemption from this change of use for the Central Activities Zone, the Isle of Dogs, Tech City and the Royal Docks Enterprise Zone must be retained.
"Without this exemption, there is a very real threat to the future of nationally and internationally significant business locations."
If the government decides to go ahead and scrap the exemptions, the four organisations are calling for a change to the "prior approval" system that is used to consider office-to-residential PD applications.
This would "allow local planning authorities to consider the impact of the significant loss of the most strategically important office accommodation within a local area," the letter says.
Under the existing rules, councils can refuse office conversion prior approval applications on grounds relating only to transport and highways impacts and flooding or contamination risk.
But according to the DCLG consultation, a new "tightly defined" prior approval test would be added to these after May 2016 to allow local planning authorities to "consider the potential loss of the most strategically important office accommodation".
The letter suggests a process to allow councils to decide the "most strategically important office accommodation" in their area.
Within the defined areas, which would be approved by the government, change of use from office to residential would not be permitted development.
The process would firstly involve the communities secretary identifying "broad criteria for the allocation of strategic office locations", including assessing the importance of the area to the local and wider economy.
Councils and the Greater London Authority would, if they wish to do so, "assess and define the most strategically important office accommodation" in their area, consult on the draft locations and then notify the government of their proposals. The communities secretary would have the power to modify the assessment if he was not satisfied.
The letter states: "The Mayor, POS London, the BPF and London First believe that this approach would strike the right balance between identifying and protecting strategically important office accommodation and keeping the administrative burden of doing so to a minimum."
In response, housing and planning minister Brandon Lewis said: "The government’s change of use reforms are providing badly needed homes such as studios and one-bedroom flats for young people, especially in London where there is a particularly acute need for more housing. Our reforms are helping promote brownfield regeneration, protect the Green Belt and increase housing supply at no cost to the taxpayer.
"We will carefully consider all responses to the consultation. We recognise that there is some nationally strategic office space, such as in the City of London and Canary Wharf, and we will review how the current exemptions are handled moving forward."