MOTORISTS using the A1(M) this evening (Thursday) are being warned of “considerable delays” due to the Sonisphere Festival taking place at Knebworth Park.

Gates at the stately home opened to early campers at 3pm this afternoon, and queues of traffic on the motorway north of WGC has been building steadily ever since.

Junction 7 is now partially closed – the southbound exit slip road and northbound entry slip road – to assist pedestrian access across the bridge.

A Highways Agency spokesman said: “The early arrival of many concertgoers due to the fine weather is causing considerable delays which will be exacerbated by the arrival of rush hour.”

* Latest traffic information is available by calling the Highways Agency Information Line on 0300 123 5000.