It sits like an early Christmas present for trainspotters.

Wrapped in large sheets of white plastic, the first of the new trams for Sydney's $2.1 billion light rail line from the central business district to the south east has secretly arrived at a new stabling yard under construction near Randwick Racecourse.

The consortium building the light rail line would have succeeded in hiding its presence ahead of an unveiling by the government but for eagle-eyed local residents, who were intrigued by what was underneath the white wrapping.

Assembled in France by transport conglomerate Alstom, the front section of the red-coloured Citadis X05 – complete with driver's compartment – now at Randwick will eventually be coupled to another vehicle to form a 67-metre light rail tram.