What does 'smart casual' actually mean for men?

I’m 26 and have landed my first proper job – but I don’t understand the office dress codeEvery week a Guardian Money reader submits a question, and it’s up to you to help him or her out – a selection of the best answers will appear in next Saturday’s paper.I’m a 26-year-old male who has landed his first proper job, but my heart sank at the dress code: smart casual. What does that actually mean? Blazers and chinos from Marks & Spencer? I don’t h