Steering wheel shake!

Hi everyone i'm VERY new here and really hoping all you knowledgable peeps can help me!

Right i have a 2001 TD5 disco GS, which i love to bits, however recently it has developed a shake on the steering wheel at around 55mph, can vary but generally aroung this speed. You can drive out of the shake, hope that makes sense, if you accelerate or decelrerate but if you want to stick at a constant speed there is a definate shake/vibrations which are quite bad sometimes and worrying me.

I have had they tyres checked, wheel balance checked, tracking and wheel bearings checked all are fine ??
Can anyone please help me diagnose what is wrong with Lionel (my disco)

Also does anyone know of anyone who is reliable and reasonable to fix him in the vecinity of Northwich in Cheshire

I had this on my D1 at 64mph, changed the steering damper but just masked the problem, I had the wheels balanced which did cock all as they were fine, in the end it was the Swivel pre load. They add or take away shims to make it harder to turn, I think it's around 6Kg force before they should move, havent got the RAVE to hand so can't check.

But Disco 2s don't have swivels Steering damper just unbolt it and see if there's resistance and no flat spots, then fit the rear wheels on the front to see if theres any change. Also check wheel bearings, ball joints.
Theres more but you will need a manual.

OK thanks guys,

As i'm a useless woman i'll be directing my other half (who incidently owns a garage)so what do i need to tell him???? In simple terms please

My Bad lol.