We met a couple on site last Easter who had bugs in a Bailey Unicorn,they were in all the window seals, light clusters, and every small crevice,apparently they were the size of ladybirds,and they thought they had come from woodland where their caravan had been stored,we found a couple under our groundsheet when we left.From memory their van had come from a dealer somewhere near Milton Keynes although I could be confused about that bit.