Sir Robert. . . .
You never mentioned the housing / casing style or its dimensions, the latter of which, tells you a lot.
Smallwood is still a viable manufacturing firm out of Canada.
There is referencig placed below to a PCB mount style of transformer and you can see that they are still starting with the miniscule 2.5 VA rating and stepping on up, in which case you see the secondary current capabilities initially ~ doubling up in current values.
I don't ever remember seeing an 47 / 1847 lamp being used in a Pincess'es'es phone . . . its lamp access was thru a slot indented rotary. . 1/4 turm plastic disc on its bottom . . . . .which then was seen to be housing a socket for a "push in--pull out" "wedgie" lamp, with its folded wire leads, style of # 259 lamp.
INFO:
http://www.sgsmallwood.com/downloads/TR1 series.pdf
73's de Edd