It sounds like the RCAHMS might have a rather flawed security system. If this is the case, they can hardly complain about deep linking, which is inevitable.
There's nothing illegal about linking to a web page. If someone appropriates the contents of the page in a way that breaches the copyright then the fault doesn't lie with TMA.
A lot of people seem to think that, if there's no copyright information explicitly associated with an item, it's somehow fair game. Obviously this isn't the case. All material is restricted by copyright, unless otherwise stated.
There's a separate question as to whether or not it's wise for us to be deep linking into the RCAHMS site. If they change their URL structure, we'll be faced with quite a problem.
K x