"Maybe these ladies will be a little wiser and think before they speak," he wrote in the post, adding the hashtags #blacklivesmatter and #englishbreakfasttea.
"Hopefully there won't be a next time!"
The post was shared on Facebook, attracting more than 13,000 reactions, 1500 shares and 1200 comments, the overwhelming majority of which have been positive.
"Being kind often does help. It sometimes shames people into looking at their behaviour. It makes them feel guilty for being d*ckheads," one user wrote.
"If I was there I would have given you a standing ovation with lots of clapping and cheering," wrote another. "Hope the ladies have learned some serious lessons from this incident because in this time and age there is no room at all for these kind of remarks."
His mother, Trish Hill Wall, wrote: "I'm so proud my son that you rose above the hurtful rants of others. Kindness goes a long way, and you all walked away after with your heads held high."
There was a tiny oversight though, when Mr Wall realised he'd ordered a pot for one.
"Hopefully they filled their cup though," he wrote with a winking face emoji.