Could the 38 stock and the 59 stock be coupled together?

Hybrid trains have existed at various times - the "58" standard stock trailers inserted into 1938 stock trains, and at different times stnadrd and 1938 stock trailers in 1960 stock not to mention the G/K/L/M/Q stock melanges that characterised the District Line right up until the late 1960s. But these required extensive modification to work together.

It is possible to couple different stock using emergency coupling adaptors, but usually only the assisting train can provide power and brakes. It is sometimes possible for the failed train to retain it's braking system depending on the nature of the failure, but not to operate the brakes on the assisting train.

On the DR C/O/P stock could couple to the east end of R stock using the Wedgelocks, but we had to use isolating pads to prevent electrical coupling. West end R stock only had a Ward coupler and could directly couple to Q stock, though no electrical or brake connections were possible.

The last red surface stock (CO/CP stock) was withdrawn in 1981. (R stock followed two years later, although of course "crusty" didn't say the silver train was R stock: it could have been C or D stock.

R stock was originally painted red, and for a while only the aluminium-bodied R49 vehicles were silver: the older all-steel R38 and R47 vehicles (and all but six of the DM cars were R38s) were still painted red. Until the 1960s it was therefore common to see trains with a mixture of red and silver cars although this one ( i.guim.co.uk/static/w-300/h--/q-95/sys-images/Guardian/Pix/pictures/2012/10/23/1350989610404/first-aluminium-bodied-R4-007.jpg ) was a one-off for the Festival of Britain!