Built by the Allied Marine & locomotive Company in 1975.

By 1972, YEOMAN had been returned to steam, but PRINCESS required a greater restoration than was possible at Boot Lane at that time.
Rose decided what he really wanted was a new build steam locomotive that he could rely upon, and after a little research, he found the Allied Marine & locomotive Company which was prepared to tackle such a project.
Drawing inspiration from the Penrhyn Mainline Hunslets; but as now running on the Ffestiniog Railway with tenders. Rose & Allied Marine agreed upon a design and the new engine was delivered to Candlebridge in the Spring of 1975.
The locomotive was named BUTTERFLY by Rose and was such a success that Rose arranged for Allied Marine to restore/overhaul PRINCESS.

Specifications –
0-4-0 ST
Cylinders – 7″ x 12″
Driving wheels – 24″ (dia)
Boiler pressure – 160 psi
Tractive effort – 2940lbs (@75%bp)

Operational status –
awaiting overhaul