The London Mayoral fast track route was intended to bring clarity and momentum to London’s planning system. Hit fast track and you avoided a late-stage review (LSR). Miss it and the Mayor would want a meaningful share of any upside if you out performed business plan. In a rising market there was an argument to be made for such an approach, particularly on multi-phased schemes.
Yet, in 2026, development economics is challenged and policies that seek to put pressure on delivery need to justify their worth. What’s becoming apparent is this framework lacks transparency, relies on incomplete data, and is struggling to respond to changing market conditions.
Fast track philosophy under scrutiny
Under the Mayor’s Threshold Approach, schemes that meet specified affordable housing levels can access the Fast Track Route, avoiding detailed viability assessments and late-stage reviews. The objective was straightforward: embed affordable housing expectations into land values and speed up planning decisions. On paper, you can understand the thinking.
However, political scrutiny at City Hall is now revealing uncomfortable gaps between policy intent and policy outcomes. At Mayor’s question time end of last year, when asked how many fast-track permissions have actually been implemented, the Mayor confirmed the Greater London Authority does not hold this data. For a mechanism so central to the London Plan, the absence of basic monitoring raises serious questions about how success is being measured.
More striking still is the Mayor’s confirmation there are currently eight schemes subject to Section 73 applications seeking to amend permissions originally granted through the fast-track route. These are not anecdotal examples but recorded cases where schemes are returning to renegotiate because they can no longer meet the affordable housing thresholds agreed at consent. This points to a structural issue: fast track assumes a level of market stability that recent cost inflation and financing pressures is undermining.
Late stage reviews – are they yielding?
Late-stage reviews, intended as flipside to not taking fast track, fare no better under scrutiny. Designed to capture uplift if schemes perform better than expected, they have become a mechanism whose scale and effectiveness are largely unknown to the policy makers which conceived them.
At the same question time, the Mayor acknowledged the GLA does not know how many planning permissions across London include late-stage review clauses. There is also no data on how many schemes have progressed far enough for reviews to be triggered.
When pressed on outcomes, the data also remains thin. Since the viability SPG was introduced in 2017, only £3.5 million has been identified as secured through late-stage reviews, with the explicit caveat that borough-level monitoring is incomplete and likely under-reports actual sums. This is a remarkably modest return for a policy so frequently cited as a safeguard for public value.
What this all means
Reflecting on the ambiguity and lack of data, it is difficult not to conclude that the London planning system is not evaluating what policies are aiding delivery and which are not. It feels like fast track is losing credibility as schemes fall back into renegotiation, while late-stage reviews deliver neither financial certainty nor demonstrable impact at scale from a public purse perspective.
If London is serious about accelerating housing delivery, it must confront an urgent truth: complexity without transparency undermines confidence. A clearer upfront settlement, backed by proper monitoring, may deliver more homes in practice than a system that relies on mechanisms it cannot meaningfully measure. The Temporary Measures are a positive start, but there is more that can be done.
