Lady Campbell — who has written three biographies of the late Princess Diana — said: “Everything I hear is that Harry is completely beguiled by Meghan and completely enthralled to her.”
Based on her insider knowledge, she also claimed that Prince Harry had “changed considerably” since marrying Meghan.
The former UK I’m A Celebrity … Get Me Out Of Here! contestant added: “People do change when they get married.”
Lady Campbell’s latest comments follow claims that Meghan has “banned” her husband from “drinking alcohol, tea and coffee”.
Meghan is said to have limited her husband’s alcohol and caffeine intake in favour of mineral water as the couple prepare to welcome their first child in the British springtime.
A source told the Express: “Considering he’s been a pretty brutal drinker since he was a young teenager, it’s quite an achievement.”
What’s more, Prince Harry is also believed to have taken up yoga and is trying out a vegan diet at his wife’s request.
Back in March, Meghan is said to have persuaded Harry to quit smoking.
Ahead of their wedding in May 2018, Prince Harry is believed to have shouted “what Meghan wants, she gets” at royal staff.
According to royal biographer Robert Jobson, the Duke of Sussex was so “stressed”with wedding preparations that he became “petulant and short-tempered” with those around him.
Meanwhile, Meghan “left Kate Middleton in tears” over her strict demands for Princess Charlotte’s bridesmaid’s dress, according to royal sources.