Question: Where does the grand union canal start and end?
Disambiguated questions and answers: question: Where does the main part of the Grand Union Canal start and end?
Where are the start and end points of the arms of the grand union canal?
answer: Starts in London, ends in Birmingham
Leicester,  Slough, Aylesbury, Wendover, Northampton
Natural Questions answer: starts in London
ends in Birmingham (from the Wikipedia article "Grand Union Canal")