Sam Altman, the famous Silicon Valley-based tech venture capitalist, was asked to leave a bar at The Ritz because he was wearing sneakers. The Ritz, famously, has a strict formal dress code: "Gentlemen are required to wear a jacket and tie ... trainers and sportswear are not permitted in any of the hotel or Club’s restaurants or bars."

He tweeted a picture of the offending training shoes:

—Sam Altman (@sama) 7 June 2016

Altman is the president of Y Combinator, one of the biggest VC funds in the US. Y Combinator has backed Airbnb, Dropbox, Zenefits and Stripe.

Paul Graham, Altman's cofounder at Y Combinator (who also happens to be English) suggested that the Ritz incident meant that London just wasn't on the same level as San Francisco and Northern California:

—Paul Graham (@paulg) 7 June 2016

It's likely that Graham was trolling because he is English, and thus knows full well that you cannot just show up at the world's most famous hotel dressed however you like.

But the tweets started a semi-serious debate on Twitter about the way tech funding has changed San Francisco but not London. Altman and Graham's tweets prompted dozens of responses. Benedict Evans, the cantankerous analyst at Silicon Valley VC fund Andreessen Horowitz (another transplanted Brit), suggested Altman was in the wrong place:

—Benedict Evans (@BenedictEvans) 7 June 2016

Because this took place on Twitter, some people took it waaay too seriously, with Americans generally arguing that dress codes for bars are outdated and Brits generally arguing that Americans don't know high standards when they see them:

—Sue Spence (@virtualsue) 7 June 2016

Some people, however, got it just right. Here's Christian Hernandez, founder at VC firm White Star Capital:

—Christian Hernandez (@christianhern) 7 June 2016

(Double monks are a type of posh shoe with buckles instead of laces.)

Altman took it all in stride:

—Sam Altman (@sama) 8 June 2016