The original Colin the Caterpillar cake has achieved national treasure status. For the past 35 years, the delicious, simple-to-slice creation from Marks & Spencer has been a fixture at birthday parties for youngsters and grown-ups alike. Far simpler to portion into equal slices than a conventional round birthday cake and, at £10, still relatively budget-friendly, Colin has charmed his way into Britain's affections. Colin boasts some famous admirers too. David Beckham famously marked his 43rd