Cool Baby Product: The Tot Seat - why didn't I think of this? - http://www.totseat.com/english/home/
Portable fabric sling turns any chair into a high chair.
Tot Seat - Coffee Bean £24.50 http://www.beebiesbabystore.com/#!product/prd1/1161146631/totseat---coffee-bean
Make a material foldup high chair for cafe's - just pop in your tote and always prepared.