Ok, stripped the Longbow down, degreased, checked over, relubed and fitted together and the bl***y thing will not cock. Pulled apart several times to inspect, but no joy, still not latching.
It looks as though the safety is being activated too soon and so stopping the trigger cocking. I`ve give up for today. I will have another go tomorrow. In the meantime if anybody has a suggestion it will be well received. I did cock the trigger before installing by the way.