Hillingdon Council’s decision to approve a borough-wide Article 4 Direction for Houses in Multiple Occupation (HMOs) represents a decisive shift in how residential property can be repurposed across one of West London’s most active rental markets.
For many years, landlords relied on permitted development rights to convert standard family homes into smaller HMOs without the need for planning permission. This flexibility underpinned a large volume of professional HMO investment, particularly in commuter boroughs where demand from sharers, airport workers, contractors, and international tenants has remained consistently strong.
That position is now changing. Once Hillingdon’s Article 4 Direction is fully confirmed, planning permission will be required for most HMO conversions, regardless of size. This is not a marginal adjustment to process. It fundamentally alters acquisition risk, funding structures, timelines, and exit strategies for landlords operating in the borough.
At Willow Private Finance, we are already seeing lenders, valuers, and investors recalibrate their approach to HMO assets in Article 4 areas. This guide explores what Hillingdon’s decision means in practice in 2025, why councils are increasingly adopting this approach, and how experienced investors should adapt.
The expansion of Article 4 Directions across England reflects a broader shift in housing policy. Local authorities are under sustained pressure to balance competing objectives: supporting private rental supply while protecting housing quality, neighbourhood character, and local infrastructure.
In boroughs like Hillingdon, private renting has grown rapidly over the past decade. Alongside this growth has been an increase in informal or “hidden” HMOs, where properties operate as shared accommodation without clear planning oversight. Councils argue that national permitted development rights have limited their ability to manage this growth effectively.
From a political and planning perspective, Article 4 is seen as a corrective tool. It allows councils to scrutinise where HMOs are located, how dense they become within particular streets, and whether proposed conversions align with local housing strategies.
For investors, the key takeaway is this: Article 4 is no longer an exception—it is becoming the norm in high-demand rental markets. Hillingdon’s move places it firmly within a growing group of London boroughs applying stricter planning control to HMOs.
The most significant impact of Hillingdon’s Article 4 Direction is the removal of permitted development rights for converting a dwelling house (Use Class C3) into a small HMO (Use Class C4).
Previously, many landlords could convert properties for occupation by three to six unrelated individuals without planning permission. Under the new regime, that automatic right no longer applies across the borough.
Once confirmed, all new HMO conversions will require a planning application, regardless of size. This applies to both first-time HMO projects and portfolio landlords expanding existing holdings.
Importantly, Article 4 does not ban HMOs. It introduces a planning gateway that must be passed before use can change lawfully. However, that gateway introduces uncertainty, cost, and time—factors that directly affect investment viability.
Hillingdon Council has cited several drivers behind the decision, all of which align with national policy narratives.
A key concern is over-concentration of HMOs in certain neighbourhoods. Councils increasingly argue that excessive clustering can undermine community cohesion and reduce the availability of traditional family housing.
Housing quality is another major factor. The council has referenced evidence of poor conditions and serious hazards within parts of the private rented sector. Requiring planning permission gives authorities greater leverage to influence standards indirectly, even where licensing applies separately.
There are also concerns around anti-social behaviour, parking stress, and pressure on local services, particularly in areas with high transient populations.
To support its position, Hillingdon commissioned an independent housing tenure survey, which identified a significant rise in private renting and a substantial number of unregistered or poorly monitored HMOs. From the council’s perspective, stronger planning control was a justified response.
The Article 4 Direction has been approved by full council and will be introduced as soon as possible. Following introduction, the council must undertake a statutory consultation period and then seek confirmation from the Secretary of State after a minimum of six months.
While transitional arrangements may apply depending on submission dates, landlords should not rely on timing strategies to bypass the new rules. In practice, lenders and valuers are already treating Hillingdon as an Article 4 borough when assessing risk.
For investors considering acquisitions now, the assumption should be that planning consent will be required, and that funding must be structured accordingly.
A critical point often misunderstood by landlords is the distinction between planning permission and HMO licensing.
Planning permission governs use of the property. HMO licensing governs how that use is managed, including safety standards, room sizes, and landlord competence.
Hillingdon is also consulting on a borough-wide additional HMO licensing scheme, aimed at improving standards and accountability. This is separate from Article 4 and applies regardless of planning status.
In practical terms, many landlords will need to satisfy both planning and licensing regimes. Failure on either front can render a property unmortgageable or unrefinanceable.
From a lending perspective, this dual compliance requirement has become a standard underwriting consideration, particularly for professional HMO lenders.
Existing lawful HMOs are not automatically rendered unlawful by the Article 4 Direction. However, that does not mean they are immune from future scrutiny.
Material changes—such as increasing occupancy, reconfiguring layouts, or extending properties—may trigger planning assessment. In some cases, even refinancing can prompt closer examination if planning status is unclear.
Landlords relying on future value uplift through reconfiguration should revisit assumptions carefully. In Article 4 areas, the planning risk is no longer theoretical—it directly affects asset liquidity.
Valuation methodology is evolving rapidly in Article 4 boroughs.
Where planning consent is unconfirmed or uncertain, valuers may adopt a restricted or alternative use valuation, rather than an income-based HMO valuation. This can materially reduce loan proceeds.
Lenders have responded by tightening criteria. Many now require:
Clear evidence of lawful use
Planning consent where applicable
Conservative loan-to-value ratios
Shorter terms or staged facilities
This has particular implications for bridge-to-let strategies, where planning approval is a key condition of refinance. Without consent, exit risk increases sharply.
At Willow Private Finance, we increasingly structure HMO funding using phased approaches—short-term capital to acquire and stabilise assets, followed by longer-term finance once planning and licensing positions are secure.
Article 4 does not eliminate opportunity, but it raises the barrier to entry. Investors who rely on speed, minimal due diligence, or aggressive leverage will find Hillingdon increasingly challenging.
Conversely, experienced landlords who engage planning consultants early, model conservative timelines, and structure finance appropriately may benefit from reduced competition and improved long-term stability.
In some cases, constrained supply can support rental resilience for compliant HMOs. The key is aligning investment strategy with regulatory reality, not resisting it.
Willow Private Finance advises landlords and investors operating in complex planning and regulatory environments, including Article 4 boroughs across London.
We work with specialist lenders who understand HMO risk, structure funding around planning uncertainty, and support clients through acquisition, refurbishment, licensing, and refinance stages.
Our role is to ensure that finance supports strategy—not undermines it—particularly where regulatory change alters the risk landscape.
Q1: Does Hillingdon’s Article 4 Direction ban HMOs altogether?
No. It requires planning permission for new HMO conversions but does not prohibit HMOs outright.
Q2: Will existing HMOs need planning permission retrospectively?
Generally no, provided they are lawfully established, but changes or intensification may require consent.
Q3: Is planning permission required for small HMOs of three or four tenants?
Yes. Once confirmed, the Article 4 Direction removes permitted development rights regardless of size.
Q4: Can I still get a mortgage on an HMO in Hillingdon?
Yes, but lenders may require stronger planning and licensing evidence and may offer more conservative terms.
Q5: How does Article 4 affect HMO valuations?
Valuers may apply restricted or alternative-use valuations where planning consent is uncertain.
Q6: When will the Article 4 Direction be fully enforceable?
Following consultation and Secretary of State confirmation, typically after a minimum six-month period.
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About the Author
Wesley Ranger is the Director of Willow Private Finance and has over 20 years of experience in property finance. He specialises in complex and high-risk lending scenarios, including HMO portfolios, development projects, and planning-sensitive acquisitions. Wesley works closely with landlords, developers, and professional advisers to structure finance solutions that remain viable under evolving regulatory frameworks.
Important Notice
This article is provided for general information purposes only and does not constitute financial, legal, or planning advice. Planning policies, mortgage criteria, licensing requirements, and regulatory interpretations vary by local authority and individual circumstances and may change at any time.
You should always seek tailored advice from qualified planning, legal, and financial professionals before committing to any property or financing decision.
Willow Private Finance Ltd is authorised and regulated by the Financial Conduct Authority (FCA No. 588422). Registered in England and Wales.
