A header assembly for attachment to a feeder house of a combine harvester for movement in a forward working direction across a field carrying a standing crop to be harvested, the header assembly comprising: a header comprising: a header frame; a sickle cutter bar carried across a front of the header frame for cutting standing crop; a reel for carrying the crop over the cutter bar; a crop transport device for transporting the crop inwardly from ends of the header to a collection location for feeding to the combine harvester; a mounting arrangement for mounting the header frame on the feeder house of the combine harvester; first and second ground engaging gauge wheels on the header frame one on each side of the feeder house; the ground engaging gauge wheels being mounted on the header frame at a position spaced rearwardly of the cutter bar; first and second adjustable links for adjusting the height of the first and second gauge wheels respectively relative to the header frame in response to a height input; an angle adjustment member for tilting the header frame forwardly and rearwardly about an axis transverse to the forward working direction relative to said mounting arrangement in response to an angle input; a control system operable by a driver the header being characterised in that the control system includes a driver interface arranged for input by the driver of: a first input acting to set a value of a required height of the cutter bar from the ground; and a second input acting to set a value of required angle of the header relative to the ground; the control system including a program responsive to the first and second inputs (45, 46) for generating said height input to said first and second adjustable links and said angle input to said angle adjustment member to automatically obtain said set a value of a required height of the cutter bar from the ground and said set a value of required angle of the header relative to the ground. a header comprising: a header frame; a sickle cutter bar carried across a front of the header frame for cutting standing crop; a reel for carrying the crop over the cutter bar; a crop transport device for transporting the crop inwardly from ends of the header to a collection location for feeding to the combine harvester; a header frame; a sickle cutter bar carried across a front of the header frame for cutting standing crop; a reel for carrying the crop over the cutter bar; a crop transport device for transporting the crop inwardly from ends of the header to a collection location for feeding to the combine harvester; a mounting arrangement for mounting the header frame on the feeder house of the combine harvester; first and second ground engaging gauge wheels on the header frame one on each side of the feeder house; the ground engaging gauge wheels being mounted on the header frame at a position spaced rearwardly of the cutter bar; first and second adjustable links for adjusting the height of the first and second gauge wheels respectively relative to the header frame in response to a height input; an angle adjustment member for tilting the header frame forwardly and rearwardly about an axis transverse to the forward working direction relative to said mounting arrangement in response to an angle input; a control system operable by a driver the header being characterised in that the control system includes a driver interface arranged for input by the driver of: a first input acting to set a value of a required height of the cutter bar from the ground; and a second input acting to set a value of required angle of the header relative to the ground; a first input acting to set a value of a required height of the cutter bar from the ground; and a second input acting to set a value of required angle of the header relative to the ground; the control system including a program responsive to the first and second inputs (45, 46) for generating said height input to said first and second adjustable links and said angle input to said angle adjustment member to automatically obtain said set a value of a required height of the cutter bar from the ground and said set a value of required angle of the header relative to the ground.