1. A method of data processing in a data processing system, the method comprising: at a cache memory of a data processing system, receiving a speculative memory access request, the speculative memory access request including a target address of data speculatively requested for a processor core; in response to receipt of the speculative memory access request, transactional memory logic determining whether the target address of the speculative memory access request hits a store footprint of a memory transaction; and in response to determining that the target address of the speculative memory access request hits a store footprint of a memory transaction, the transactional memory logic causing the cache memory to reject servicing the speculative memory access request.