Lorry Drivers are beginning to wind me up.......

Twice today I have been tailgated by lorries.  First one this morning going through the tunnel on the A3.  There is a 40mph speed limit through it, but the lorry behind which was actually a car transporter was practically sitting on my back bumper.  The second was coming home on th M3 through the roadworks betwwen Junction 4 and the Junction 2.  The weather was atrocious, I was doing 50mph as per speed directions, yet this one was driving right up to me and almost trying to push me to go faster.  I had to move to the middle lane anyway to carry on the M3 and he undertook me, only to have to slam his brakes on because the traffic had ground to a halt in front of him anyway.  What is wrong with these people.  I am not going to exceed the stated speed limit and get another speeding ticket.  Do I have to display a notice in the back window saying this.  It seems to me that every time there is a pile up on a motorway, a lorry/lorries are always involved.  What happened to the Gentlemen of the Road.   Rant over.