Intriguing! The bridge is owned by Wandsworth so presumably SW15, but does land in SW6. And Putney Bridge Underground Station is in SW6.There is a website of a company appearing to be in Plymouth which uses SW15 on their Tees: https://putneybridgelondon.com/I suspect you've found a generic international (made in China?) 'brand'. I've seen a few odd slogan T shirts in non-English countries.
Alan Sherman ● 1633d