GADM

Middlesex has 12 third level subdivisions

third level divisions

Map ID	Name
1	Lucan Biddulph
2	North Middlesex
3	Middlesex Centre
4	Thames Centre
5	London
6	Adelaide Metcalfe
7	Strathroy-Caradoc
8	Oneida 41
9	Chippewas of the Thames First Nation 42
10	Munsee-Delaware Nation 1
11	Southwest Middlesex
12	Newbury