Rail Warrants are still around, though now generally only used by the MOD for Season Tickets, and things like Social Services, Prisons, Courts, and the Probation Service.
Companies that would previously have used warrants have generally moved to using Travel Management Companies, Online Retailers or just buying tickets on the day of travel.
I didn't know that, thought that they went out with B.R..
Interestingly, although they removed the risk to the employer of the employee fraudulently reclaiming more than had been expended, the system gave an opportunity for fraud by the booking clerk - although, in those days, being caught would result in instant dismissal without recourse to any appeal.
Manned barriers did not always manage to ensure those with devious intent always gave up their tickets. There were refund claims (which could then be made, and instantly settled, at the booking office) on return tickets when only the outward half was cancelled, the reason being the assertion that 'I returned by car'. Never having been offered a lift home when in a distant town myself I had a cynical view of this claim. Some satisfaction could be obtained, however, to view the look of surprise when the calculation was made; in the case of, for instance, a day return the refund was for the difference between the price of that and a single (not, as was sometimes expected, of half of the price) to which was added the administration charge. Because the difference in price between the two was small and the admin. charge significant, usually the total was a negative amount (i.e., the passenger owed us some cash) but I always offered, as a gesture of goodwill, to waive this charge