Nice summary of the history of Westminister township.
https://en.wikipedia.org/wiki/Westmi...ounty,_Ontario
I would add that the City wanted the northern end of the township that bordered on them and were not interested in the southern end that bordered on Elgin county. The province rightly decided that the remainder was not fiscally viable so they ended up making the City take nearly all of the former township.
This part of London is not attractive for development due to being downwind of 3 waste treatment/landfills. Hence why we have seen all the new residential development happen in the NW, North and East sides of London. For the same reason we have seen bedroom communities like Mt Bridges, Komoka, Kilworth, Arva, Thorndale, Ilderton grow with new housing developments. The pressure will grow in the coming years for discussions about municipal services in those areas bordering London. I have no doubts that the County will fight hard to not give up these areas in an annexation.