The Southern only DaySave ticket (£10 anywhere on their trains only)
was mentioned here in connection with their new website.

SWT yesterday emailed me (new mailing list now their free mag has gone)
about a similar offer, £10 day return "to anywhere on our network"

Midsummer Madness, weekends in August except Bank Holiday w/e.

£5 child, no railcard discount but available in advance or on the day
and someone had done the work to make them available from the
self-serve ticket machines.

"Tickets are issued as a Day Return and are valid on South West Trains
services only. They are valid between any two stations served by South
West Trains, except the following: stations west of Honiton; stations
between Warminster and Bristol Temple Meads inclusive; or to/from the
Isle of Wight."

So Salisbury/ Stonehenge, Portsmouth, Southampton, New Forest,
Lymington Bournmouth/ Poole, Weymouth but not Exeter or Bath

--
Mike D