On Saturday March 24th 2007 WHR (Caernarfon) held a day of special events for Phase 4 Appeal sponsors, on the day before the start of the main season. The highlight was the first operation of passenger trains over almost the entire length of track laid so far south from Rhyd Ddu, giving sponsors the opportunity to see otherwise inaccessible locations, and to get a taste of what awaits fare-paying passengers in 2009. This was an unusual and involved exercise even once the authorities had granted special permission.
It was realised that the state of readiness of the track was not yet up to taking a Garratt further than Pont Cae'r Gors cutting, so the two Hibberd "Planet" diesels Upnor Castle and Conway Castle headed the train and did the honours beyond there, propelling back uphill, with carriage no. 1001 at the north end, once again proving its worth as a vehicle suited to push-pull working thanks to its brakesman's lookout. Rather than using the modern WHR(C) carriages, nos. 23 and 24 were strengthened by "toastracks" nos. 37, 38 and 39 specially moved from the FR for the event; as well as being light, their short-wheelbase bogies make them quite forgiving of track conditions.
The first test for the event was carried out on Wednesday March 21st, when no, 138 Mileniwm/Millennium took Upnor Castle (fresh from maintenance at Dinas) to Rhyd Ddu. Upnor then took a test rake comprising nos. 24, 23, 1000 and 1001 to the far end of Cwm Cloch cutting, just short of where the Head of Steel had reached the weekend before.
A second test ran the next day, with Conway Castle and two of the toastracks added to the formation.
Sponsor's Day turned out to be a perfect Spring day. Two sets of workings ran, with the morning trains for Gold and Silver sponsors, and the afternoon ones for Bronze. The morning train hauled from Caernarfon by no. 138 was joined at Waunfawr by Castell Caernarfon with five of the six carriages for the "Forest Train", giving an unusual formation with the train loco sandwiched behind them while the Funkey served as pilot.
No. 1001 was added to the Forest Train at Rhyd Ddu (no. 1000 was not used on the day), and with passengers having signed waivers on the way from Caernarfon, the train set off with some assistance from no. 138 at the rear, before dropping off the Garratt at Pont Cae'r Gors.
Unlike the tests, the train did not enter Cwm Cloch cutting but terminated just north of it, some 6.3km from Rhyd Ddu, with views downhill onto Beddgelert village. The track gang were required to be clear of the Head of Steel when the trains were nearby, giving them the opportunity to have a look from the trackbed on the middle section of the lower S-bend.
The train then reversed back uphill to Pont Cae'r Gors, from where no. 138 piloted the train back to Rhyd Ddu.
Sponsors where then taken on by coach to Porthmadog via Phase 4 sites visible from the road, to sample the WHR(P) Traeth Mawr extension and get a walking tour of sites on the Cross-Town Link, before being returned to Caernarfon by coach.
In the meantime, Castell Caernarfon had returned to Caernarfon to bring up the sponsors on the afternoon train, for their trip onwards to Cwm Cloch and back.
With two trains in the platform - and arrivals from the south - Rhyd Ddu gave an impression of how it will look as a passing place from 2009 onwards. The afternoon return train also made full use of the length of the platform, with the two trains combined giving a length of fourteen carriages, with Castell Caernarfon sandwiched between the two sets, and Conway Castle at the top end. Upnor Castle was detached at Pont Cae'r Gors, to work back down to the Head of Steel to collect the works train comprising carriage no. 1000 and the SAR van at the end of the day's tracklaying; Dolgarrog's works train was also to follow.