There has been much amusement at the sight of Madonna (net worth £580m) taking a budget flight from Lisbon to London, but I am not sure why.

I’ll bet her decision was not about cost, but appearing on-trend. Air Portugal is by far the cheapest option on this route, with tickets costing from £42 in economy. Madge could have chosen Easyjet, Ryanair or British Airways but they all cost more for the 2 hour 40 minute flight.

I suspect the Material Girl has finally realised that travelling in close proximity to the public is good for your brand – Rihanna set the benchmark by travelling to her sold out O2 gig on the underground in 2011, and then did it again in 2013. On each occasion she stood for the entire journey wearing high heels and dark glasses and posed for countless pictures with fans. Each journey was a brilliant PR event which sent social media into a frenzy.

Chris Martin and Jay Z (wearing a heavy gold chain, not something I’d recommend for the outer reaches of zone 6) followed suit, and Harry Styles, Emma Watson and Eddie Redmayne have all been snapped using public transport.

Guess what? Famous people regularly go shopping too – I am amused by an anecdote I once heard of a celebrity followed to the supermarket checkout by a fan, who then complained “I can’t believe all you’re buying is toilet rolls!”. They received the answer “isn’t it extraordinary – I sh*t, just like everyone else”.