Now, a purist might object that this is ungrammatical and argue that it should say: 'No shoes or slippers' rather than 'No shoes and slippers', for the rule in Standard English is that or rather than and is used after a negative. Furthermore, some might argue that there is a useful distinction between 'No A and B' (which indicates that either A or B is OK, but not both together) and 'No A or B' (which indicates that neither A nor B is OK). According to this interpretation, the sign suggests that you can wear shoes or slippers into the building so long as you don't wear them both!Yeah, yeah. The problem with this is that everyone understands the sign perfectly well, and moreover the rule I just gave, that or not and should be used after a negative, is pretty obscure. And this rule does not seem to apply in most varieties of New English emerging around the world.
I predict that, in the future when New Englishes are likely to have an increasingly important role in the development of the language, 'No shoes and slippers' will become perfectly acceptable, and only a few out-of-touch purists will try to cling to the traditional form.
Languages evolve all the time, and this is just the kind of simplifying change one would expect to occur in the evolution of English. The only new thing here is that this change seems to be originating in the New Englishes of places such as Brunei rather than the UK or USA.
