Huge triangular craft with with hundreds of star like lights in sets of 3 covering under side.

Large triangular craft size of football pitch when directly over head could not see night sky the craft was moveing south to north no sound from the engines. As we looked at the underside there was a border of blacknes that followed the triangular shape then starting from the tip of the triangle one set of 3 lights grouped together in a triangle as bright as stars then 2 sets of 3 lights then 5 sets 7 sets and so on filling the whole triangle.Which in fact made the craft stand out against the clear night sky, hundreds of lights in strait lines no matter what angle you looked at the craft your eyes followed the lines of lights. Infact if the lights had been random the craft would have been invisible.
Witness indicates that the date of the incident is approximate.  PD