Hello, Richard.
The slate tops on Irving Kaye tables are always made in one piece. The base is not suitable for holding a three-piece top rigidly over time. The base is made only of thin laminated boards, which is typical for pool tables used in the hospitality industry, and not of thick solid wood, like, for example, Brunswick or the AMF Grand Prix from that era. These frames are rigid enough to support a three-piece top without any changes in the base over time due to the high weight of the slate. On 8 ft Irving Kaye tables, the top is 22mm thick and weighs about 300 pounds. Smaller tables, like the 6 ft model, only have 18mm thick tops weighing 200 pounds. I hope this answers your question sufficiently.
Regards, Valero