I've calculated the metropolitan area of Manchester, UK by using INSEE's definition of the metropolitan areas (see post #427 above).
As was the case for London, the Manchester metro area attracts only very few towns. It is surrounded by urban areas strong enough to resist its pull. The only urban areas that it attracts (40% commuter threshold) are Marple, New Mills, and Westhoughton. Warrington and Macclesfield are definitely not part of the Manchester metro area (only 13.7% of residents from the Borough of Warrington who are in employment commute to the metro area of Manchester; only 23.1% of residents from the urban area of Macclesfield who are in employment commute to the metro area of Manchester).
Of note, the Manchester metro area does not include the urban area of Wigan (but it does include parts of the Metropolitan Borough of Wigan which are either physically joined with Manchester or attracted enough by it as is the case with Westhoughton). The urban area of Wigan is physically separate from the urban area of Manchester, and strong enough to resist its pull (only about 15% of its residents in employment commute to the Manchester metro area despite the fact that the latter includes nearby places such as Hindley, Westhoughton, or Bolton).
In total, the metro area of Manchester covers all of the Greater Manchester metropolitan county except for the western part of the Metropolitan Borough of Wigan, and it extends in places beyond Greater Manchester because some towns lying across the border are part of the built-up area of Manchester, and therefore of its urban area and metro area (such as Glossop, Wilmslow, or even Newton-le-Willows in Merseyside). The borough of High Peak in Derbyshire is the one whose territory is the most engulfed by the Manchester metro area. The metro area stops sharply at the border of West Yorkshire (not even a village beyond the border is attracted by the Manchester metro area).
And now the figures you were all waiting for.
Built-up area of Manchester (defined at the Output Area level):
- land area: 630 km²
- population (March 27, 2011 census): 2,553,379
Manchester urban area (defined at the MSOA level, which is equal to French communes):
- land area: 1,331 km²
- population (March 27, 2011 census): 2,569,033
Manchester metro area (INSEE definition, 40% threshold):
- land area: 1,470 km²
- population (March 27, 2011 census): 2,639,762
For comparison:
Lyon metro area:
- land area: 6,019 km²
- population (Jan. 1, 2011 census): 2,188,759
Lille metro area (French part + Mouscron and Comines-Warneton in Belgium):
- land area: 1,027 km²
- population (Jan. 1, 2011 census): 1,232,602
The Manchester metro area resembles the Lille metro area a lot. A conurbation surrounded by other urban areas strong enough to resist its pull, and therefore a small metro area (in terms of surface). For example in the case of Lille, the Lille metro area fails to attract the nearby urban areas of Armentières or Carvin (Armentières is as close from the center of Lille as Marple from the center of Manchester, yet less than 40% of its residents in employment commute to Lille contrary to Marple where the 40% threshold is crossed). The Lille metro area attracts only a few smaller urban areas such as Orchies or Wavrin.
Lyon, on the other hand, is a typical French metro area surrounded by rather empty countryside and therefore free to expand for miles and miles without being blocked by other urban areas (although whenever it meets a significant urban settlement, its expansion does get blocked, such as in the case of Vienne which blocks the expansion of the Lyon metro area towards the south).
Next I will calculate the metro area of Birmingham. We will finally be able to solve the mystery of which city is the 2nd largest in the UK.