I hesitate to comment in detail on this interesting issue because (a) I'm not knowledgeable about British law regarding access for the disabled, and (b) I don't know how much of the published information to believe. I have no reason to question the intent of the reporters who've been covering the Cutty Sark story, but topics like this have so many subtle complications that they often get distorted by the time they reach the public. And I've seen several "artists' versions" of the plans for the new facilities in the "drydock"; I don't know which of those are just ideas that were floated at one time or another, and which, if any, represent what's actually going to be done. (For that matter, I'm not at all sure the responsible parties have decided what the finished product is going to look like.) I would, however, like to offer some generalized comments that may be relevant.
I think I can claim to sympathize with the concept of "disabled access"; I've got some physical problems that make it tough for me to get around in some circumstances, and I certainly don't think people confined to wheelchairs ought to be denied access to anything unnecessarily. I repeat: I don't know what British law says about the subject. But I do know something about American law as it relates to the subject, and I suspect the British equivalent is similar.
I teach a college course in historic preservation planning (i.e., the preservation of old buildings). One of the basic laws affecting that field is the Americans with Disabilities Act (ADA) of 1990. The Department of Justice maintains a big website that covers it pretty thoroughly: http://www.ada.gov/ . In most respects (there are obvious exceptions), ships are covered by the same ADA provisions that govern buildings.
The basic idea behind ADA is that public facilities (i.e., those to which the public is routinely admitted - whether publicly or privately owned) are supposed to be "accessible" to the disabled. In practical terms, that means a person in a wheelchair has to be able to get into all parts of the building that are accessible to other members of the public (albeit not necessarily by the same route). That means, in turn, that elevators, or ramps of a specified grade, have to be provided as alternatives to steps, and openings such as doors have to be at least four feet wide.
When ADA was passed there was a brief wave of panic among historic preservationists. Installing an elevator or a wheelchair ramp, in addition to being expensive (sometimes extremely expensive), obviously can require gutting an old building - to the point where the very nature and character of the building cease to exist. Fortunately, however, somebody involved in the writing of the law had the sense to figure that out. The law contains language that grants exceptions in the case of historic structures: "Alterations to historic properties must comply with the specific provisions governing historic properties ..., to the maximum extent feasible. [My italics.] Under those provisions, alterations should be done in full compliance with the alterations standards for other types of buildings. However, if following the usual standards would threaten or destroy the historic significance of a feature of the building, alternative standards may be used." Some such "standards" are spelled out in more detail, but in plenty of cases the people in charge of the structures, sometimes with the help of the State Historic Preservation Office, have to figure out for themselves how to bring those structures into compliance.
Nobody's quite sure what all the implications of ADA for old buildings are in the long run. In the American legal system, the detailed meaning of laws only gets established when those laws get "tested in court" - i.e., when somebody gets arrested for violating the law and tries to convince a federal court that either (a) he really didn't violate the law, or (b) the law is unconstitutional. So far there haven't been any big, decisive, landmark cases involving ADA and historic structures. So the people responsible for operating historic buildings - and ships - are interpreting the law as best they can, and hoping for the best.
There's just no way the U.S.S. Consitution could be made entirely, or even mostly, wheelchair accessible. The same goes for the Charles W. Morgan, the Star of India, and, for that matter, the U.S.S. North Carolina.
The people in charge of historic structures are obliged to make a good-faith effort to provide the disabled with some form of "alternative" to access to the parts of the structure that aren't accessible to them. Some years back, in the museum studies course that I teach, I had a student who was confined in a wheelchair; it was most interesting to see the provisions that various historic sites we visited on field trips made for her. At Tryon Palace, for instance, a ramp (which was carefully located so the general public didn't see it) gives wheelchair access to the first floor. The tour guides have a big notebook full of color photos of the other floors; while one guide takes the other visitors in the group upstairs, another shows the photos to the person in the wheelchair. The U.S.S. North Carolina has a wheelchair ramp that gives access to the main deck - but that's as far as the wheelchair-bound can get. At Jamestown Settlement, visitors watch a video that shows the interiors of the Susan Constant, Godspeed, and Discovery. (Anybody who tries to take a wheelchair on board one of those little ships is out of his/her mind.) And so forth.
So far, in the twenty years since ADA was passed, that's been satisfactory. The truth of the matter is that wheelchair-bound visitors to museums and historic sites tend to be extremely reasonable folks, and, in every case I've observed myself, understand the problems of accessibility and appreciate the efforts the sites make on their behalf.
Tryon Palace and the three Jamestown ships present especially complicated cases, because technically they aren't "historic properties." Tryon Palace is a replica, built in the 1950s on the foundation of the original, 18th-century building; the current Jamestown Ships are only a few years old. I suppose it's conceivable that, sometime in the future, some judge could rule that they aren't in compliance with ADA. But that hasn't happened yet - and it doesn't seem likely.
All this, of course, means nothing to the case of the Cutty Sark, because she isn't covered by American law. But I suspect Great Britain has something quite similar to ADA.
I have trouble reading the various artists' renditions of what's planned for the drydock, and I'm not sure those pictures are reliable in any case. (I have the impression that the plans are still very much a work in progress.) I do know that a big doorway was cut in the ship's side at 'tweendeck level back in the 1950s, when she was put in the drydock. At least one of the drawings I've seen on the ship's website seems to show the wheelchair ramp leading through that door. There's been talk of an electric elevator, but it seems to appear in some of the pictures and not in others. Two additional holes were cut in the hull back in the fifties; I wonder if they're going to be utilized somehow in the new construction. In other words, it may - may - be that making her "handicapped-accessible" will just entail re-using the openings that are already there. I certainly hope so.
I don't think anything in British law requires gutting the ship so wheelchairs can roll around all over her. (If such a law did exist, what would have to be done to the Tower of London? Or Hampton Court? Or Windsor Castle?) I suspect that, in fact, the law would prevent such a thing from happening. (If Mystic Seaport ever decided to gut the Charles W. Morgan in such a manner, the people from the National Trust for Historic Preservation and the National Register of Historic Places would land on the institution's management like a ton of bricks. The Morgan is a National Historic Landmark.)
Up until quite recently I was a hundred percent confident that the people running the Cutty Sark restoration were operating in strict accordance with the ethical and professional standards of the preservation/conservation field - and I still think they were. The recent news stories, and especially the resignation of the engineer in charge of the project, have me worried. I continue to hope, though, that common sense and professional ethics will win out - and/or that the journalists don't quite have the story straight.