Phil, Graham,
Sorry for the delay in replying. Yes, it is a public park Phil but the dog walkers and joggers are well used to the anglers. Graham, it's the Woodmill to Mansbridge stretch immediately below the Lower Itchen Fishery stretch at Gater's Mill. If you park in the huge car park near the White swan pub, look at the pub and immediately to the left of the pub is a swim where the river curves round the back of the pub garden. There is a crease on the inside line where the fish tend to lie up and also a clearly seen gravel patch directly in front of the swim half way across the river. A trot down the crease will bring grayling as will a blockend feeder on the gravel. Double red maggot to a 16 hook with a 3lb hooklength (chub about!!) and 4lb reel line. If you are feeder fishing you will need a 2oz quivertip.
You can walk along the stretch and there are various glides and eddies which you can fish - the choice is yours really. From the car park, look at the pub and to the right of the pub (upstream) you will find a stretch that is also productive. Don't worry about the streamer weed - put you feeder in it, that's where the fish are! During the autumn when the weed has died down a bit, this is a very good stretch to trot. But be aware of the sea trout. These things fight like stink and will trash your swim!!!!