The two bodies have been at loggerheads in recent years following a disagreement about using a section of WHR track to take WHHR passengers along the newly reopened WHR from Porthmadog to Caernarfon.
WHHR officials had been openly critical of the refusal of access but a change of leadership has led to a more conciliatory approach.
Martyn Owen, Chairman of the WHHR
, said: "We're really pleased both original plates are now back in Wales."
chairman Martyn Owen said a special Welsh dragon-themed event over the August Bank Holiday attracted many extra visitors.
chairman Martyn Owen said: "It might seem strange to have a dragon theme to a weekend at a steam railway, but you never know what is lurking inside the firebox of some of those engines."
Since it opened, the WHHR
has been operated almost entirely by volunteers.
chairman James Hewett said: "We are very unhappy the Ffestiniog Railway Co, despite many previous promises, has now denied us the opportunity to run our passenger trains on a railway which we helped build.
James Hewett, chairman of the WHHR
, said: "We're delighted that Gertrude will be joining us for the coming season.
spokesman James Hewett said: "The loco was part of a project called the Lower Lea Valley Cable Tunnels (Olympics).
Among the four is James Hewett, who's been spending Christmas Day at the WHHR
for the last six years.
Over 200 people also came to ride on the WHHR
ghost train, a special event for Halloween, which started as an experiment in 2008, and proved to be so popular, it was repeated this year.
Martin started being a town crier in 2000, and moved to the WHHR
at the start of this year.