Now change the rules so that in future only 75000 short-term visas are issued each year. In the first year, there will be 75000 arrivals and (still) 100000 departures (people whose visas were issued under the old rules and who were already here). But in the next year, there will be 75000 arrivals and 75000 departures. Measured net PLT migration will have been 25000 lower than otherwise in the first year, but is not different than otherwise in the years beyond that.