The early version of the Britannia model came in green livery - a few shades lighter than the Brunswick Green of later models.  In 1980 Minitrix introduced a brand new model to the British Range - The Mallard. Although at first glance the chassis and the design looked very similar to the Early Britannia, in fact it the chassis was altered in a number of subtle ways. Primarily, the gearing was higher. I suppose that the Mallard, being the fastest steam engine on the tracks really ought to be able to go around the track faster !

But this meant that cogs on the drive wheels, the idler gears, the holes for the axles, the plastic drive gear between the motor and the wheels all had to be changed. These newer chasses red double cog with one cog larger than the other. The original Britannia model have a black double cog with both cogs the same size. SInce this gear is just visible at the 1 o'clock position of the rear left drive wheel, it is the easiest way to spot a new or old chassis.

The front end was also different - adopting the larger spoked front bogies, and gone was the solid brass underplate in preference to the plastic one with moulded brake fittings. The crank pin on the centre drive wheel is now plastic,with a square peg compared to the metal splined crank pin of the original Boadicea. The body is exactly the same moulding as the original Britannia - as far as I can tell - but it now has the smarter, darker Brunswick Green colour.

The Minitrix number for the early Britannia as 51-2037-00. The later Britannia became 51-2037-10 but Hornby marketed them as simply N203. The same chassis would now be used for all of the Minitrix Pacific (4-6-2) models: The Briannia had adopted the new Mallard chassis, and the subsequent models of Sir Nigel Gresley, Boadicea, and the two varieties of Flying Scotman would all share essentially the same basic chassis.