After 'Your Majesty', Meghan will be allowed to refer to the Queen as 'Ma'am', which Ingrid claims can then be formed to 'Mama.'
'This can be shortened to Mama , when Meghan gets to know her as Diana did. But never her pet name Lillibet, which is reserved for very close family and friend,' she said.
Kensington Palace told the Daily Mail that the Duchess of Sussex is not yet referring to the Queen by the nickname 'Mama', but according to experts she could use it as she settles in to her role.
Judging by their interactions on Thursday, however, it appears it won't be long until newly-married Meghan will be on 'Mama' terms.
The close bond between the Queen and Meghan became apparent when the pair sat down at a ceremony to open the new Mersey Gateway Bridge.
Judi James, a body language expert, revealed to the Daily Mail that Her Majesty appeared 'completely confident' in Meghan's ability.
She said: 'The Queen is quite stoic, she didn't make a fuss of Meghan, which can make someone feel anxious. She is clearly completely confident about Meghan's level of confidence.
'They were very relaxed. At one point they were giggling like teenagers together. The Queen looked delighted to be with her.
'The Queen was doing everything right for her and made her looked like a granddaughter or a friend whom she is very fond of.
'She was almost identically fun loving and relaxed with her first outing with the Duchess of Cambridge, that's what it reminded me of. It looks as though it really brought out the Queen's fun side.'
Tom Ingham, a psychotherapist, added, 'The body language of the Queen and Meghan is warm, friendly, they look to be enjoying the time they are spending together.
'There is formality to the occasion as they step from the train, but the overall tone is relaxed and warm.'
