Hi all, fixed now new washers did the trick! Had to go to mercedes dealership to get them it was only £2!!
I may also add that they have to be done up extremely tight I broke a ratchet tightening it (was a cheap one) but non the less, so used good old fashioned spanners one on the bolt and and one on the filter
It hasn’t been changed in 25 years and the car runs much smoother at idle.
Thanks for the replies