Battery / mains portable with flip-front dial, sometimes known as the Flip-Front, or Picnic Radio.
Note, there is a loop antenna mounted behind the dial in this model - in subsequent models it ran around the inside of the front half of the case.
Battery: Eveready 753 dual-A-and-B pack, 9V and 90V, similar to this:
There is a switch on the back to select battery or mains operation, and then the on-off switch is incorporated into the dial, so the radio comes on when the dial is opened.
Colours - Ivory, Brown (Burgundy), Grey / Ivory, Mint Green / Ivory, Baby Blue / Ivory and Red / Ivory (mention of a gold coloured one in advertising, but never sighted).
CAUTION: The cabinets on these sets are fragile, and undamaged cases can be hard to find - especially the backs. Due to their age the handles should not be trusted, carry them carefully.
Based on an American model by Zenith - the "Tip Top Holiday" model 4G903:
Image from Wikimedia
And also sold in Australia as the Technico Pacemaker model 1259 or TO.8:
The Leader series of portable valve radios was first introduced by Collier and Beale in 1950 and went through 3 different versions. It was developed from the American Zenith model 4G903, and was sold in Australia under the Technico banner as the model 1259 and TO.8.
They ran on mains or a combined AB battery that supplied 9V for the filaments and 90V for HT.
A quick way to identify which of the three models you have is to check the dial. If there is a round metalic badge screwed on over the dial pointer hub then its probably a 5150AB, if there is a tone control in the same place then its a 5155AB, otherwise its probably a 5153AB.
The radios in this series are:
Intermediate Frequency: 455kc/s
Frequency Bands: 1
General Construction Notes for Collier & Beale Ltd:
Model numbering followed no real sensible scheme until around 1940 - and prior to 1934 apparently no model numbers were assigned at all.
From 1940 a 3- or 4-digit system was employed where the first digit indicates the number of valves, the second digit is the number of bands and the third is the year of manufacture. From 1950 the last digit became two digits, eg: 5151 is a 5-valve broadcast-band only from 1951.
From 1957 model numbers were replaced with model names, ie the Pacemaker Buffalo - which makes the year of manufacture hard to determine unless service info is consulted (although C&B often released service info after the radio, and the date on the service info was for its release, not that of the model.