Type soundness for denotational semantics of state

Mads Tofte's thesis contains a (now classic) proof of type
soundness for a language with state, based upon an operational
semantics.  Where would I go to find the same proof for a
denotational semantics, analogous to Milner's original proof
that well-typed programs cannot go wrong?  Thanks, -- P

Philip Wadler                             wadler@research.bell-labs.com
Bell Laboratories             http://cm.bell-labs.com/cm/cs/who/wadler/
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