Alan Goodwin confirms it is approaching Vauxhall with the up 'Bournemouth Belle' - the bottom of the platform ramp can be seen at the very bottom of the photo.
He adds "I think this is the evening of June 15th 1967, the last time an original Bulleid Pacific worked this train"

Geoff Catlin’s almost identical image on Bulleid Society website confirms details but gives the date incorrectly as 16th June 1967