Oxford University has said it is “deeply sorry” after a female cleaner was pictured removing chalk graffiti saying “Happy International Women’s Day”.

Sophie Smith, the associate professor of political theory at University College, shared a picture of the scene on Twitter, writing: “What an image for #IWD.”

The university replied to the professor in a tweet saying the incident should not have happened. “We are deeply sorry for this and for offence caused. International Women’s Day is hugely important to Oxford. This should not have happened.”

Oxford security makes a woman cleaner scrub out “Happy International Women’s Day” on the Clarendon steps. What an image for #IWD, @UniofOxford. #strikeforUSS #UCUstrike pic.twitter.com/E9u5S37hWW — Sophie Smith (@DrSophieSmith) March 8, 2018

Smith thanked the university for the apology but said she hoped the cleaner, whose face she obscured in her tweet, received “a heartfelt apology”. She called on the university to ensure that all low-paid staff at the institution earned enough money to live in Oxford.

“I appreciate your apology, but far more importantly can you please make sure that the woman asked to remove the message receives a heartfelt apology, a warm cup of tea, the rest of the day off and, along with all our precarious staff, good enough pay to live in this city,” she replied.

I appreciate your apology, but far more importantly can you please make sure that the woman asked to remove the message receives a heartfelt apology, a warm cup of tea, the rest of the day off and, along with all our precarious staff, good enough pay to live in this city. — Sophie Smith (@DrSophieSmith) March 8, 2018

Garrick Taylor‏, a laboratory manager at Oxford University and the president of the Oxford UCU union, said the symbolism of the image was key to the debate.

“During a peaceful International Women’s Day rally. A low paid and probably precariously employed female cleaner was sent out in the freezing cold to clean chalk writing saying Happy International Women’s Day. Did it have to be removed? Then?,” he wrote.

But others were baffled by the university’s decision to apologise. “Are you for real? I’m assuming it’s her job as a cleaner. Why would she get an apology and the rest of the day off? That’s bizarre,” wrote one.