Have been trying for years. My father owns a 1947 Robert Clark design from James Miller (believed to be 'Inverie' class.)
I wrote to Millers before they closed but didn't get a response. I would dearly love to get my hands on the plans - we have the sail plan - so if you get any further please let me know... it'll make my old man happy.
I think I have had a result from the last round of telephone calls.
It appears the Robert Clark archive is held by the National Maritime Museum, though they may deny it, not knowing what they do possess.
The archive is at its Woolwich premises known as the Brass Foundary. The head of this department is Bob Todd, but I am told that the most helpful person there is Mary Edwards. The number is 0208 855 1647
Beware, though, that dealing with the NMM can be expensive. For private individuals it's not too bad, with Look-up fees starting at around £15 and around £20 for each drawing. We professionals face fees starting at over £90.
Surely it miust be posible to find yards that have built to his designs that have plans. Otherwise place an add on this wanted section. Is there not an owners association?
Slightly off the point:-
Was "British Steel" completely flush-decked when built? I saw her on the Dart recently with a superstructure. It just didn't seem right!
The answer to all these is no. Most of the yards which built to his designs are no longer trading. Those that are, mostly have lost the records. There is no owners association. There is no residual Rober Clark design company. I spent d=some time with the 'usual suspects before discovering the NMM link, though I must confess this was a fairly obvious place for them to be and should have been an earlier port of call
Totally irrelevant to the OP ... but just after WW2 my mum and dad chartered a Robert Clark design called Kalistra on the South coast and sailed to France in her. Many years later I saw the same boat up here on the Gareloch but I am not sure she is still there. I would like to contact the current owners as I have a photo of Kalistra by Beken of Cowes somewhere in my mountains of junk and they may be interested in it.