The ICBINB font is almost a semi-serif, almost like a sans serif that's slightly melted, whereas I'd say the crumpet is fully serif. The "e", "L" and "v" are pretty different. And I'd say the ICBINB font lends itself better to tighter spaces, whereas the crumpet font seems to beg for more space.

But certainly, I could see one being used to replace another in a pinch - but I'm not a font specialist (graphologist? Is there a word for a person who studies fonts?)

RIP Emma Chambers