The E pontoon used to have 20% off.. As Pete says, it's only accessible to the smaller craft, which is why they had a discount.. Dry berthing in the secure MoD yard at Clarence was around £90 a month for a 5.6m, (it's based on length, so including the trailer would have been closer to 6m..) Launching is fairly easy, my front wheel drive C5 used to do it, albeit with a long rope.. The slip is long, with a slight incline.. Launching on a very low tide would have been interesting though..
The yard itself is probably the safest, and most secure on the South Coast, 24hr MoD security at the gate.. There's facilities to wash the boat down afterwards, and an electrical supply to do any work thats needed.. There's a theoretical charge for using the slip, and overnight berthing at Clarence, (if you wanted to leave the boat in the water for a weekend,) though I never ended up paying any extra on top of the monthly bill..
In the main carpark at Clarence, there's a shower block/washroom/laundrette/toilet block thats always been kept V clean.. If I ever get another boat, Clarence would be the first place I would check.. All in all, definitely a 5 thumbs up rating..