The photo of "Rail Coach E" on Page 35 of Mont Lingard's book, "The Newfie Bullet", reproduced below, indicates that the cars had a centre freight section, with passenger compartments at each end. The driver's cab forward contained the boiler and highspeed enclosed engine that characterized the Sentinel design. Most Sentinel cars could be driven from either end and these were likely of that design.

The cars were used in branch line and commuter service around Corner Brook and St. John's, and lasted into the late-1 930s. They were scrapped for the usual reasons: cost savings over conventional operations were not as much as anticipated. In addition they had difficulties in the winter.
During the 1920s and 30s, Sentinel shipped hundreds of steam railcars to many countries, but these five for Newfoundland Railway were the only ones to come to North America as far as I know. The last Sentinel cars were shipped to Nigerian Railways in 1 953, closing out a 30-year production run that started with (island of) Jersey Railway and Tramway. The latter is the prototype for my working model of this very special type of railway rolling stock.

Sources:
Rowland A.S. Abbott. Vertical Boiler Locomotives. Oakwood Press (U.K.), 1989.
Mont Lingard. The Newfie Bullet. Mont Lingard Publishing, Grand Falls-Windsor, NF., 2000

Bytown Railway Society,  Branchline, November 2008, page 18.