Original idea: the window starts off with just the names 'Mark' and 'Spencer', plus a glitterball heart...
Original idea: staff then invite customers to write little love notes...
Original idea: each note is then hung in the window as a kind of performance art
Original idea: the Pride flag in love notes. And of course Mark loves Spencer...
This is a simplified version of the original idea, which is what M&S ended up going with.