We've spoken to a few people on the beach who have had their cars broken into parked on the road so we always park in the National Trust car park near the shop and cafe.  Its only a 15 minute walk to the naturist section.  Last time we were there it was £9 to park but free to NT members.

This is a very useful reply and I shall definiteley be using one of the car parks when I visit.

Just a quick warning. I posted here three or four years ago about parking in the NT car park.
We had a Suzuki Jeep at the time and when we walked back to it after a day on the beach, we found the front wheel nearly off and all of the wheel nuts loose. Somebody had thought that my front wheel would look better on their jeep.
Gordon

I regularly use Studland and tend to park in the NT car park. NT membership pays for itself if you visit as often as I do but I appreciate it's pretty expensive if you don't

Be aware that if you park on the road and are parking near the NT car park on-road with your wheels on the road (as opposed to entirely on the verge) in late 2013 the local parking people were fining cars. Not something to come back to!

I've never heard of break-ins on the road (and it is quite busy so I would have thought it wouldn't be so easy) but always NT for me. It isn't really any longer to walk along the beach than through from the fire-break at the first bus-stop along from the ferry either

Another vote for the NT car park at Knoll Beach, by the cafe. We finnd the stroll along the shore easier than the walking from Firebreak 6 on the road - a route that entails negotiating quite a lot of soft sand. From the NT car park we head down to the edge of the water; and the sand is then firm and easy to walk on along to the naturist section. We also reckon the first part of the naturist area you come to is the most family-friendly.

Mike

We have always parked on the road near to the cut through that leads directly to the naturist part of the beach and have never had a problem. Maybe it's just good luck.. enjoy