In early March 2020, Covid-19 had reached our shores and Ireland was just days away from announcing the first lockdown measures. But, while the country was consumed by the pandemic, serious concerns of a different kind were being raised in Government.

The Minister for Housing is not routinely involved in matters of national security, so it was unusual when Eoghan Murphy was called to a top-secret briefing with senior defence and security officials.

At the briefing, it was explained to the then-minister that a planned expansion of the Russian Embassy on Dublin's Orwell Road needed to be stopped.

Planning permission had been granted by Dún Laoghaire-Rathdown County Council in 2015, but a closer look at the proposals had raised red flags. The Government had recently passed legislation allowing it to block applications on national security grounds – so it fell to the Housing Minister to act.

On 4 March, just days after Ireland reported its first case of Covid-19, Minister Murphy quietly signed an order revoking part of the embassy’s planning permission.

The development was, according to the order, "likely to be harmful to the security and defence of the State and the State’s relations with other states".

There was no publicity and no press release. It was only months later that the unprecedented decision was first reported.

The move to block the embassy’s expansion, which the Russians have called "ludicrous", has come into sharp focus with the outbreak of war in Ukraine.

Prime Time commissioned architectural visualisations based on the original planning application to illustrate the scale of what was envisaged.

The footprint of the embassy would have expanded dramatically under the plans (Visualisation: Digital Dimensions)

The embassy applied to expand its footprint on its Orwell Road site to four times its existing size. In addition to two new accommodation blocks, an underground car park, ESB substation and water storage tanks, a major extension was planned to the embassy building itself. The three-storey development was a particular concern to the security officials.

"The Russians wanted to build a major compound with a major, underground subterranean complex," Cathal Berry TD, a former Army Ranger officer, told Prime Time.

That’s despite the 5.5 acre site having "plenty of room" to build above ground.

The basement, which was labeled on the planning application for storage and plant use, looked more like a "nerve centre" of the operation, according to Mr Berry.

"There's 20 storage rooms, ten power plant rooms, and four rooms with no description, which are called voids. The plans also included the provision of 13 toilets in the basement, which is considered unusual for a storage area."

"You could have the GRU, which is the Russian military intelligence, or the SVR, which is their foreign intelligence service, operating underground," Mr Berry explained.

Security sources were worried the subterranean area was ideal for storing computer servers potentially for use in data mining, troll farming and launching so-called "influence" operations.

In an interview with Prime Time last month, the Russian ambassador to Ireland, Yuri Filatov, rejected the suggestion that the embassy expansion posed a threat to the Irish state.

During the interview with Sarah McInerney, which took place at the Orwell Road complex, Mr Filatov said the 100 year-old embassy building was no longer suitable.

"We are sitting in the only reception room at the embassy – that’s it, he said. "It was not supposed to be an office or embassy."

Mr Filatov said he hoped "common sense" would prevail, adding the Russians were still in negotiations with the Irish Government to find a "workable solution".

However, the subsequent outbreak of war will have reinforced the Irish decision to revoke the planning permission.

Yuri Filatov, the Russian ambassador to Ireland, during an interview with Prime Time's Sarah McInerney

Philip Ingram, a former MI6 officer who speciliases in Russia, told Prime Time that the Orwell Road embassy is likely to be working on the war effort.

"They will be hunkering down with their intelligence officers inside the embassy," he said.

"The covert operatives that they have on the ground will be trying to find out what the thinking is within the EU and elsewhere, both from an economic sanctions perspective, but also from a military build-up perspective."

Mr Ingram said Ireland was "the perfect place" for hidden agents to carry out nefarious tasks, or from which to manage other agents.

Separate from the expansion of the embassy building itself, Russia has moved to ensure that it has constant supplies of water and fuel on the site.

A water pump station and underground fuel store were both included in the plans for the site.

"If there was a problem with Irish water from a maintenance or contamination perspective, they would be self-sufficient from water," Mr Berry explained.

While the Government revoked the permission for the embassy extension, a new consular building and the accommodation blocks were permitted.

New figures released to Prime Time show there will be no shortage of staff to occupy the buildings. Russia has the second-largest number of embassy staff in Ireland, with 30 Russians accredited to the diplomatic mission. Only the USA has more accredited embassy staff, with 37.

An aerial view of the current-day Russian embassy on Orwell Road

The Russian embassy's headcount is larger than the Chinese (25), Saudi (24), British (23) and French (20) embassies.

According to Mr Ingram, the scale of the operation is telling.

"The question that I would ask is: why are you growing? Why are you getting so big? And if you couldn't answer that from a legitimate perspective, the only answer that there could be is an illegitimate perspective."

Ireland is of considerable strategic importance to Russia, Mr Ingram said.

"You've got a lot of the transatlantic communications pipes so the Russians will be trying any operation they can to interact with those."

While the border with Northern Ireland allows easy access to the UK, a base in Ireland also offers other political opportunities.

"Ireland sits as a neutral country outside NATO but within the EU. Russia loves putting its diplomatic knife into that crack and wiggling."

Describing the staffing levels as, "completely unbalanced", Mr Berry noted that there are only a few thousand Russians living in Ireland.

"Trade links between Ireland and Russia are very small. We actually do more trade with the state of New Jersey in the United States than we do with all of Russia. So it's completely out of kilter," he said.

"You have to ask yourself, why would that be the case?"

In contrast to the 30 accredited staff in the Russian embassy in Dublin, there are just four Irish diplomats currently in Russia.

Protests outside the Russian embassy earlier this month

"There should be a matched number of Russian nationals in the Russian Embassy in Dublin as Irish nationals in the Irish Embassy in Moscow," Mr Berry argued.

Accepting that a cohort of Russian diplomats should remain here, Mr Berry thinks there are others based in the Dublin embassy that should be expelled.

"Many of them have no connections to diplomacy. They should be absolutely sent home."

It wouldn’t be the first time Ireland had packed the bags of Russian diplomats.

Following the Salisbury poisonings in 2018 and a passport fraud scandal in 2011, the Government revoked the visa of a Dublin-based Russian diplomat.

And, in 1983, three Soviet embassy staff were expelled when a spying operation was uncovered. At the time, the expulsions were not explained publicly, and most presumed they were linked to Soviet-IRA links.

But, in his memoirs, former taoiseach Garrett FitzGerald revealed that the Irish Government had been briefed that Soviet spies were exchanging information with a US double agent in the Stillorgan Shopping Centre in Dublin.

Although Russia's plans to build the extension in Dublin were stopped, the questions haven’t.

Why did an embassy representing just a few thousand citizens want a building of that size, with an underground network of rooms on a site with plenty of space to build up?

The Government stepped it to prevent the expansion. Given the current conflict, an even closer eye is now being kept on the activities at Orwell Road.