A former royal security staffer is urging Prince Harry and Meghan Markle to proceed with caution amid a perceived threat to the royal family following the Sussexes’ return to the UK.

“The threat to the UK and its assets, of which the Royal Family is one, is currently severe,” former Met Police bodyguard to the British royal family, Simon Morgan, exclusively told Page Six Thursday.

“Being discreet and unobtrusive is really important — you don’t want to unsettle the environment, as that causes problems,” he said.

Morgan further assessed that Harry’s recent security concerns stem from both concrete threats and his understanding of the risks associated with his royal ties.

Describing them as “actual risks,” Morgan pointed to Harry’s status as a prince, as well as a former military officer who served two operational tours.

“[Harry] publicly discussed killing Taliban fighters in his memoir,” Morgan noted, saying that the royal vet could expose himself to “genuine security threats.”

At the same time, being a public figure with a high net worth inherently creates “perceived risks” to Harry’s family, finances and social standing, Morgan continued.

“Therefore, they seek to reduce and mitigate the risks by using security [and] professionals whose job it is to deal with these threats,” he said.

Morgan, who founded special security team Trojan Consultancy, factored in how the Duke and Duchess of Sussex became polarizing people after they quit their royal duties and moved to California in 2020 — only to return to the UK six years later in August.

“If we look at the Sussexes’ visibility over recent years, they have alienated large sections of the public [and] everyone has an opinion,” he said. “Most are negative, some positive and some don’t care.”

But negative public sentiment does not necessarily translate into a credible threat of physical harm, Morgan explained, adding that determining whether that hostility poses an actual danger is a matter of intelligence.

Having worked in royal protection as well as the private sector, Morgan knows that the Sussxes’ security team most likely created an “operational plan.”

Morgan said the most effective security team would be one that “can adapt when things change.”

“That plan needs to be evaluated and it needs to evolve according to changes, intelligence, environmental, media, principals, global events. You can’t just create a plan and stick with it no matter what,” he said.

He commended Markle and Harry for abruptly pulling their kids — Prince Archie, 7, and Princess Lilibet, 5 — from their new private school after just two days due to a security risk earlier this week.

“Ultimately, the Sussexes’ team has done that by changing schools. It wasn’t working, the risks were too great, they couldn’t be mitigated, so a change was needed,” he said.

However, Markle ran into more security troubles when her personal phone number was reportedly leaked after joining a WhatsApp group for parents of her kids’ new school.

“Given who the Duchess is, her personal number should not have been given out, as that is now compromised and could lead to all sorts of problems based on intelligence leakage around that number,” Morgan said. “A third-party option should have been considered.”

As for whether Harry and Markle will be able to maintain a private life despite being public figures, Morgan said “it is possible.”

“Many people do it, but there are risks associated with A-listers … And you have to identify the risks and create a security plan accordingly,” he urged. “That ultimately takes time and money in reality.”

“The higher the profile, the more factors to consider, the more resources that are needed and ultimately the greater financial resources and commitment that is needed,” he said.

Harry — who has been fighting for taxpayer-funded police protection in the UK due to security concerns — and Markle quietly moved out of the $14 million Montecito mansion and back to England at the end of August.

His father, King Charles III, made it clear that his son and daughter-in-law would remain private citizens upon their return, reminding the public that they abandoned their working royal roles in 2020.

On Thursday, Harry made his first official appearance after relocating to the UK, attending the Invictus Spirit Gala Dinner & Awards at the Old Royal Naval College in Greenwich, London.

Page Six reached out to reps for Harry and Markle.