In the 1950's I lived in North Harrow and think the Met had only two tracks
running between Harrow on the Hill and Moor Park and beyond. A recent photo
shows a second set of lines on the south west side of the station.

Clive's UndergrounD Guides web pages say "Traffic on the Metropolitan was
heavy enough that it was quadrupled from Finchley Road to Kilburn in 1913,
Wembley Park in 1915, Harrow in 1932, Northwood Hills in 1961, and
Croxleyhall Junction (north of Moor Park) in 1962." I am right in
understanding this to mean that the second pair of lines were built in 1961.

Does any one have information on this second set and/or any images of their
construction.

TIA Dave Rowsell Lower Hutt NZ