Dave Kent, a senior official at the charity Guide Dogs, has been blind since the age of 18, and says he was told to leave the popular High Street store in Mortlake.
According to accounts, a security guard asked Mr Kent to leave the M&S store last Friday.
Mr Kent highlighted the continuing problem of blind and partially blind people being told to leave stores and public buildings over their guide dogs, a move, which is in fact illegal.
A recent survey by the charity suggested up to 75 percent of guide dog owners have faced similar problems in their own right.
Marks & Spencer has since issued an apology to Mr Kent, stating their security team was wrong to ask him to leave.
Mr Kent has written to the chief executive of M&S, Steve Rowe, urging the company to inform its security team of their legal duty to allow free access to guide dogs and their owners.
Mr Kent had been shopping with a friend to buy summer clothing when the incident took place.
Faldo, a Golden Retriever, had been wearing his working regalia at the time of being asked to leave the store.
Mr Kent refused to leave the store and asked to speak to the manager, where he received an apology and a free drink.
Speaking of the incident, Mr Kent said: “A cup of tea. I just thought don’t patronise me.
“Every time this happens, it’s a kick in the nuts.
“All I want to do is go to Marks & Spencer and do what any seeing person would do in the course of their day.
“And I want to do it unhindered.
“I am sickened by these security guards.
“M&S know very well their obligations under the equality duty.
“But the problem arises with guide dogs with these third party security companies they employ.
“They’re probably on a low wage, but they’re not taught.”
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In his correspondence to M&S boss Steve Rowe, Mr Kent wrote: “Whilst the response from the manager was polite and measured, this incident left me feeling utterly wretched.
“To be publicly humiliated in this fashion in sight of other shoppers and members of staff, left my dignity in tatters.
“Guide dogs are provided to visually impaired people to support them with freedom and independence.
“And to be challenged in this way, when all I wanted to do was to go about my lawful business unmolested, like any other citizen, is absolutely unacceptable.
“It is imperative that you instruct the people you employ as your security personnel to be fully cognisant of your corporate responsibilities regarding the admittance of guide dogs and other assistance dogs, in the vain hope that this vile situation should not happen again.”
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Chris Theobald, public affairs and campaigns manager at Guide Dogs, said: “It is completely unacceptable and illegal for a business or service to refuse entry to a customer with a guide dog, yet, sadly, it happens all too often.
“Our research shows that three-quarters of guide dog owners have been illegally turned away, and this discrimination is leaving people with sight loss left out of life.”
A spokesperson for M&S said: “What happened is unacceptable and we sincerely apologise to Mr Kent.
“Our stores should be accessible for everyone and we welcome assistance dogs.
“We have worked with the Royal National Institute of Blind People to develop online assistance dog awareness training, which all of our colleagues complete.”
The statement concluded: “We are picking up with our security providers to ensure guards across stores are fully aware of our approach and are contacting Mr Kent to apologise directly.”