Rear End Noise

Got a strange one have a noise from the N/S rear wheel its like a clicking sound but a bit more intense the sound in intermittent and goes up and down with speed the sound does not appear until done about 5 miles from cold. l would have bet it was a bearing but took it to our local garage ( who are very good ) who say no play in the bearings tyres are ok and the calipers look ok. Dont know where to look next as these things are expensive to repair at the stealers. Maybe ABS problem speed sensor or could the bearing make the noise without any visible sign of play but to my mind once a bearing has gone the noise would be there all the time not intermittent