A man shouted a racist slur at her partner's lover after she broke their open relationship rules by sleeping with a black man, a court heard.

Christopher Dalby, 47, and his Southampton girlfriend Amber Gilfoy had agreed they could both play away but she could not have sex with any black men.

But Southampton Crown Court heard she did do this - with an explosive, booze-fuelled and racist row erupting at The Social pub in Bedford Place when the man walked in.

The man - referred to in court as "Mr Marshall" - walked into the bar while Dalby was four pints in to a night out with Amber and pal Safia Uddin.

Prosecutor Annabel Hazlitt said Dalby followed the man - repeatedly shouting a racist slur. Ms Uddin got involved before Dalby pushed her - and he was then led away by punters.

Ms Uddin burst into tears when he called a racist term for someone who is south Asian. He later sent her abusive Facebook messages.

In a victim statement Ms Uddin, who said she grew up in a small town but felt welcome in Southampton, said: "That night changed things for me.

"Being called this took me right back to a place as a scared child.

"I immediately broke down in tears."

Mitigating, Lisa Bowles, told the court that Dalby had been out with his girlfriend of one year and had drunk three or four pints.

She explained that Dalby has PTSD, anxiety and depression and had suffered an "autism meltdown" during the argument with his partner's lover due to the ensuing crowd that formed.

She added: "He says he is absolutely mortified. He is ashamed and embarrassed."

The incident lasted between 9.30pm-10pm on August 14 last year.

Sentencing, Judge Dan Pawson-Pounds said: "It is clear that your actions took her (the victim) back to a time she had experienced racism as a child.

"She describes her sense of shame and embarrassment.

"I am not impressed with your argument that her actions left you no choice; that is nonsense."

Dalby denied racially aggravated intentional harassment but then changed his plea to guilty.

Dalby must serve a 12-month community order with 25 rehabilitation activity days and pay a £200 fine. 

Judge Pawson-Pounds added: "I have given you a chance to make sure this doesn't happen again.

"I am satisfied you will take that chance, don't make the court look foolish."

Dalby, now of Longacre, Ash, Surrey, has previous convictions from 2012 and 2013 in France for burglary, arson and assault.