Gale-force winds and rough seas have forced the abandonment of the journey by sea which was to bring the foundation stone for the Wales Millennium Centre (WMC) from the north to south of the country.

The inscribed slate was intended to travel from its quarry in Bethesda, Gwynedd, to Cardiff Bay by horse and cart, steam train and boat - traditional methods used during the height of the slate industry.

We are susceptible to the same problems encountered by the 19th century traders Wales Millennium Centre spokesperson

But the slate had been marooned in Porthmadog harbour over the weekend due to deteriorating weather conditions.

Organisers decided on Monday to complete the journey by the most modern means - air.

The slate was due to sail around the Welsh coast on a period schooner, the Vilma, but the continuing rough seas mean that it will complete its journey by helicopter.

The slate finally arrived in Cardiff on Monday afternoon, in time to be laid on Tuesday in a symbolic ceremony at the new arts centre site by international opera star Bryn Terfel.

A spokesperson for the Wales Millennium Centre said: "We are susceptible to the same problems encountered by the 19th century traders.

"But fortunately for us, 21st Century technology means that we have better options than just sitting it out in port for weeks or months on end. "

The helicopter collected the presentation slate and BBC Wales journalist Grahame Davies, who has been chronicling the journey on behalf of the centre.

The slate finally arrived by helicopter

On Tuesday, Bryn Terfel will join the Spirit of Penarth RNLI lifeboat and crew, in bringing the slate from the Port of Cardiff, by water through to the Oval Basin quayside in Cardiff Bay.

Terfel will lay the stone at the under-construction arts centre in recognition of the contribution made to Welsh culture by the slate quarrying communities of north Wales and formally launch the WMC's Adopt a Slate campaign.

The use of slate in the building of the �104.2m arts centre is part of architect Jonathan Adams' intention to use materials linked to Wales.

The slate was transported from the Penrhyn quarry, in Bethesda, by gravity train and steam train, before being forced to finish its journey by helicopter.

Read the final stages of Grahame Davies' diary of the slate's journey at BBC Wales News Online.