New train of 6-wheeled elliptical roof close coupled carriages for the Birmingham and Sutton service - lettering shown on end of rightmost carriage. 11 carriages - Bk3 No. 7436 on right. 3rd No. 639 next to it. Taken from nearer to the end brake than WTN425. 9-Mar-1911. Wolverton Works yard Source: CROFF WTN424