National defence chiefs have not “called in” plans for 29 flats despite warnings they could compromise security at a NATO base.

Three Rivers District Council based in Rickmansworth has agreed to the principle of new homes in Sandy Lane, near Hertfordshire’s boundary with Greater London.

But a councillor has asked authority leaders whether they gave the government a chance to rule on the application themselves, because of the potential security risk to the Northwood Headquarters.

“The Ministry of Defence objected to the planning application to build 29 flats opposite Northwood HQ,” Councillor Oliver Cooper (Con, Chorleywood North and Sarratt) wrote.

“In approving that application, Three Rivers District Council concluded that there was ‘no evidence’ it would harm security.”

Cllr Cooper added: “The decision notice appears to not yet to be issued, and so it can still be called in.

“Will this council proactively ask the Ministry of Defence (MOD) or Department for Levelling Up, Housing and Communities if they wish to call in the application and not issue the decision notice unless and until they confirm they do not wish to?”

Cllr Stephen Giles-Medhurst (LD, Leavesden) replied in writing: “Northwood HQ did submit an objection to planning permission, citing their general concern of overwatch and line of sight into the main entry point from the development.

“Their objection was taken very seriously, and the case officer met with representatives from Northwood HQ to discuss their concerns.”

He added: “The case officer circulated emails to members of the said committee advising that a timescale up to Friday, May 26 would be provided for the secretary of state to call in the application.

“On May 30, the case officer confirmed that the head of establishment at Northwood HQ did not wish for the secretary of state to call in the application as they were unable to provide any further security justification.

“Consequently, the council has already offered the MOD to call in the application.”

Cllr Giles-Medhurst said developers are waiting for the final sign-off due to “discussions” over affordable housing provision, which could feature in a future legal agreement with the housebuilders.

Foliage may not hide views into military base buildings

According to the planning application, 29 new “luxury residential units” will replace a house which is in a state of “disrepair”.

The MOD wrote to Three Rivers District Council with an objection because the plans could “impact safety and security”.

The ministry’s surveyor wrote: “Irrespective of landscaping or foliage, the proposed construction will highly likely allow for direct line of sight onto the main entry point at Northwood HQ and potentially into key internal buildings on-site.”

Council staff noted in a report “the site cannot provide further detail on specific security arrangements – they can only express in terms of a general concern”.

They judged the proposed mitigation, with mature trees and privacy scenes on balcony areas, as “adequate”, so new flats would not “adversely affect Northwood HQ operations, especially as no specific security arrangements have been raised”.

Northwood HQ is home to HMS Wildfire, a reserve unit of the Royal Navy.

British Armed Forces have used the Hertfordshire site since 1939 and it is now the country’s principal military headquarters site.

NATO (the North Atlantic Treaty Organisation) has its Allied Maritime Command – or MARCOM – at Northwood.

It has control over the multinational Standing NATO Maritime Groups One and Two, which are normally sent to the Atlantic and Mediterranean regions for a range of tasks, both in peacetime and during conflict.

An MOD spokesperson told the Local Democracy Reporting Service: “Concerns were raised relating to the proximity of a development next to Northwood HQ.

“These were submitted for consideration during the planning application process.”