Bus Parcel Stamps. 
In the 20th century, the coverage of the railways shrank, and the frequency of service decreased. This left many people in the rural areas without a means of transportation, or a way of getting supplies from the large cities. As roads improved, buses became a substitute for railways. Bus Eireann, the government-run bus company provides service, not only for people, but also for parcels previously carried by rail. This service uses stamps to indicate payment for the service. (Figure 1). Figure 2 shows an earlier set of bus parcel stamps from the late 1950’s before decimalization.
Since the buses are run by the same entity as the railway, CIE, Coras Iompair Eireann, the bus schedules are coordinated with those of the trains, thus providing a useful and rapid service.
In Northern Ireland, a similiar situation existed. The small railroads were combined into the Ulster Transport Authority (UTA), later changed to Northern Ireland Railways (NIR). Many of the branch lines were closed as being uneconomical. The Londonderry & Lough Swilly Railroad converted into a bus line in the1960’s to serve the northwest, but eventually became part of the UTA.
These stamps were an outgrowth of the railway letter stamps and the railway parcel stamps that had been in use since the 1890’s. These stamps pay for the expedited delivery into Post Office channels, and the fee is collected by the bus. Railway letter stamps are discussed in another entry.
The Railway Letter Stamps of Great Britain and Ireland 1891-1947, Roger deLacy-Spencer.
Great Britain & Ireland Railway Letter Stamps 1957-1998, Neil Oakley, Railway Philatelic Group. ISBN 0 902667 24 2.