Dead tree with branches overhanging lane 1 of M25

A dead tree has branches which are overhanging Lane 1 of the M25 close to the A23 bridge over the M25 in Merstham. The tree is in an unused part of what is technically my garden. We have had a tree surgeon do as much as possible in the past and he came to survey it again today but his opinion is it is not safe to do without the minimum of a lane or lanes closure. It appears that someone has cut back the lower branches from the motorway side. The tree is dead it has a crack in the trunk and has fungus growing on same. We have concerns over the future safety of it particularly if we have another big storm.