A playful, subversive mood dominates the shortlist for Trafalgar Square’s Fourth Plinth. Most of the six proposals, in what is a very strong shortlist, play on notions of British identity, probing themes of heroism, heritage and conquest. The models, which include a cock (the winged variety), a cake and a kid on a rocking horse, were unveiled yesterday by Mayor Boris Johnson. Two winners will be selected next spring, with the first appearing on the Plinth at the end of next year. The six are: