"I can't believe he would do that to his wife and then take his own life. He was not that sort of type at all.
"The whole thing is very hard to believe. It has shocked the whole community and we are watching it really closely to see what happens.
"I hope the truth comes out soon, especially for the four young children who are left behind.''
Mr Lamb, a 47-year-old geotechnical engineer who had moved to Christchurch last year and had become a popular figure in local horse carriage driving circles, died four days later when he apparently jumped from the balcony of the nearby Sofitel Hotel.
He worked for GHD.
The couple's youngest son, who was in the apartment at the time of the tragedy, has denied the story about how his mother is reported to have died.
He told relatives how his mother had been leaning out of their apartment window to remonstrate with a noisy crowd in the street when she lost her balance and fell.
Speaking to the London Daily Telegraph, brother-in-law, Mark Rogerson described what the boy had seen.
He said: "On the night in question, there was a great deal of noise outside the apartment. Somebody started knocking on the ground-floor door of the building. Tilly leaned out to see who it was and to tell them to leave.
"Because of an awning at first-floor level, she could not see the door below. She leaned out further and fell.''
Mr Rogerson said er death was a terrible accident.
"Reports of an argument between Roger and Tilly shortly before her death are utterly and totally untrue - as well as being deeply hurtful to the family. There was no argument at all. It was an amicable holiday. They were discussing the possibility of relocating the family to New Zealand.
"Roger was in a truly terrible way. He was in a state of deep shock. He was wandering around almost as if he was in a trance.
"He was completely devastated. It was as if his whole life had fallen apart.
"He and Tilly had known each other since they were teenagers and had been married for 20 years. One can only imagine what he was going through.''
The couple's four sons are now back in Britain where they were being cared for by relatives.
Carriage Driving Club member Joanne Marama dismissed any suggestion of foul play.
Mrs Marama said: "He was very nice man, kind and helpful. It's very hard to understand and believe.''
Another club member and friend Chrissy Jenkins added: "All I would really like is for his young kids to find a bit of peace somewhere.''
