The financial fortunes of the Meccano company had been in decline for some time when, in 1964, a take-over offer by the Lines (Triang Toys) Group was accepted. Later that year, another colour change was introduced by the new management: yellow Flexible, Strip and Perforated plates, black Flanged and Plastic Plates and aluminium finish Strips and Girders. These latter were very easily marked, and by 1967 this finish had been replaced by the familiar zinc plating, a finish not without its problems, too. The choice of yellow and black followed typical highway construction equipment colours, and in keeping with this, each set was given a constructional theme name. The sets were packed in formed expanded polystyrene trays contained within sleeve covers.

1965 saw the introduction of Conversion Sets in the new colours, and two new motors, the Mamod-manufactured horizontal steam engine, and the Meccano six-speed Power Drive electric motor. Both units proved extremely popular. The Power Drive motor was especially useful in permitting a choice of output ratios from 3:1 to 60:1, but care had to be taken not to damage its plastic gears by overloading, particularly on the highest reduction! The gearbox was available separately. Together with a standard No. 4 Set, it formed the Meccano Power Drive Set. Plastic Meccano was introduced in 1965.

In 1967 a cheaper version of the Power Drive Set, the Junior Power Drive Set, included a simple geared motor which failed to appeal. The Super Tool Set, which also appeared at this time, was not a success. By 1967 the Meccano Magazine, which had been in decline for some time, ceased publication from the August issue to the end of the year, to be relaunched under new management in 1968. The first adult Meccano Club, the Midlands Meccano Guild, was formed in 1968.