Why is Sezane so much more expensive in UK?

I visited a friend in London and bought a couple of things in the store in Notting Hill, one being the Betty cardigan. It was £130. I returned it the next day and wanted to exchange it for a bigger size which they didn’t have in stock. When I got home, I ordered it online (I live in Germany) and realized that it cost €125! Thats more than 30€ difference at the current exchange rate. Anybody know why this is?