This shocking image of a suicidal man threatening to jump off a gantry onto the M1 motorway has been sent in to the Review by an eyewitness.

The emergency services remain at the scene, along with professional negotiators, who are trying to coax the man down.

The man climbed up an overhead sign gantry, around 50 feet above ground level, between junctions six (Bricket Wood) and eight (Hemel Hempstead), and threatened to jump just after 11.30am this morning.

All three lanes on the northbound carriageway remain closed and a further two southbound lanes have also been cordoned off.

Traffic is queuing back to junction four (Harrow) on the northbound carriageway and motorists travelling south are also experiencing severe delays.

Gary Sanderson, spokesman for the ambulance service, said: “It has caused major disruption and there is grid lock on both the M25 and the M1 motorways.

One lane was also closed on the M25 clockwise at junction 21 (Bricket Wood/Watford). Lane one (of three) has been coned off by the Highways Agency, to allow trapped traffic from the M1 to re-join the M25 clockwise. Both exit slip roads remain closed in the same location.

Pictures were taken by Review reader Peter White.