Friends say his wife and four children had planned to come to New Zealand.
GHD staff were told in an internal email that Mr Lamb had gone to the aid of his wife when she apparently slipped and fell to her death down a cliff when the couple were out walking.
When he tried to clamber down to help he slipped and banged his head.
Mr Lamb went into a coma, was taken to hospital, but never recovered and his life support was turned off, staff were told.
An unnamed GHD employee said staff were struggling to deal with the shock of an almost unbelievable story.
But French-language news sites reported Mr Lamb had jumped from the second storey of the Sofitel Hotel in Essaouira while his wife, 44, died in an Essaouira hospital after a fall from a rented house in the ancient medina four days earlier.
Mrs Jenkins said Mr Lamb's mother had told other Christchurch friends, including a woman her son boarded with in Christchurch, about the fall from the villa.
"There's all sorts of stories going around. I'm sure the truth will come out in the end,'' Mrs Jenkins said.
Mrs Jenkins knew Mr Lamb through the Christchurch Carriage Driving Club.
Mr Lamb was not a member of the club but actively attended their outings and shows, often taking photos, some of which appeared in the club's newsletter.
"He was a bloke who always had a smile on his face, a joke and say here let me give you a hand there, he was really nice.''
Mrs Jenkins said she was shocked .
"We were all just blown away by it all.''
The Lambs were on holiday with their four sons aged between 9 and 16 in the north African country.
Said Mrs Jenkins: "He was a bloke who always had a smile on his face, a joke and say here let me give you a hand there, he was really nice.''
Mr Lamb was an experienced geotechnical engineer who had his own business in England. He had been looking at purchasing a property and then moving the family to New Zealand, said Mrs Jenkins.
Christchurch Carriage Driving Club past president Barbara Maley said Mr Jenkins was ``a very pleasant chap''.
"He was really nice, I think if you asked any of the club members they'd all say the same. He had a sense of humour and was always there to help.''
Mrs Maley said she was ``absolutely gutted'' when she heard of Mr Lamb's death.
"I couldn't believe it. It's really horrible.''
Club member Pam Bennett said that when she first met Mr Lamb he instantly struck her as a genuinely nice bloke.
"He was just a kind-hearted person. A real gentleman''.
GHD spokesman Kane Dowsett said: "Out of respect for Mr Lamb's family, GHD does not wish to make any comment on this personal matter''.
Mr Lamb was educated at Birmingham University, and was used to outdoor adventuring as a keen hill runner in Great Britain.
The Ministry of Foreign Affairs and British High Commission in Wellington were unaware of the deaths.
Mr Lamb's online CV said he came to New Zealand from Pershore in Worcester, in the west of England.
Julian Maund, a former colleague in England, said the news came as a shock.
He had spoken to Mr Lamb recently and no mention of a trip to Morocco was made.
"This is pretty shocking stuff, I must say,'' Mr Maund said from Worcester.
"I had spoken to him a couple of weeks ago, and was told he was coming back.''
"It's all very bizarre.''
