Yes, by definition, if it used the European numbering system and began
with D, it was 1.4v for the filament/heater. Designed to run off dry
cells (I had a radio with those for years...a portable too!).

The valves are 26 - american type, and yes each is 1.5v at 1 amp. Not
the usual radio valves, which were more like 0.1 Amp. You could use D
cells for those. And yes, the European valves were often 1.4v like 3A5,
1LE3, DC90, DC93, DC96. DC96 had only 30mA of filament current.
The CPC link was absolutely right - probably the lowest prices. Looked
them up in my catalogue, then phoned the supplier. Cyclons (2v) should
be charged at 2.35v, and can be done so in a single stage - just needs
a very smooth supply of about 1% ripple and capable of 2 amps according
to them. Sounds like a DIY power supply would do this.