The adult Pakistani learners of English acquire a variety of English called Pakistani English (PE) at early stage of learning. The PE does not differentiate between aspirated and unaspirated allophones of English stops. Consequently, the Pakistani learners of English neutralize the English aspiration contrast and produce both aspirated and unaspirated allophones of English plosives as unaspirated. At an advance level of learning, if these learners try to acquire British English, they face difficulty in the acquisition of English aspiration contrast although the same contrast also exists in the L1 of the learners, because the already acquired variety of English (PE) intereferes in the acquisition of another variety of the same language. Thus an L1 contrast does not prime in L2 in the acquisition of the British English by Pakistani learners.