This grower is sure of this plant identification.
Clematis montana. This species is a very hardy vigorous climber native to the Himalayas and China. Bears clusters of sweetly scented, whitish-pink flowers with yellow stamens in late spring. Reaches a height of approximately 10-11m.
They are fully to half hardy. They will require a rich soil that is kept moist, but it is well drained. They should be grown in full sun, but the roots will require shade and protection from too much heat.
Climber, hardiness. Spring interest.