Ditton Slipway, Cholmley Road

Streetmap does not show Cholmley Road very well. (Shortened to 'Chol Rd')
There is actually a track to the river at the slipway - see streetview below.
Leave A307 on Ditton Reach. The Google map shows it better.
There does not appear to be a slipway at the end of Ferry Rd.

Ditton Slipway, Cholmley Road

Left bank off the A307 Portsmouth Road (see note under Streetmap above)

Ditton Reach Slipway, 1999
Ditton Reach Slipway, 1999

The boy fishing inspected the punt and decided that a 25 horsepower motor would be about right.  There had been moments in punting from Cricklade to Teddington when I would have agreed with him.
Actually a year or two (or rather forty years ago!) when with a small family I did run a punt with an outboard for occasional use, 4hp was about right - enabling 5mph - which is all legally allowed anyway!
Notice that the far bank is grass and trees.  There is plenty of greenery here. Two miles further up there are sections of apparent countryside.