A spark ignition internal combustion engine is described comprising; an intake manifold (12); a main throttle (14) for regulating the intake of ambient air into the intake manifold; an EGR pipe (42) connected between a point in the intake manifold (12) downstream of the main throttle (14) and a point in the exhaust system located downstream of the main restriction (62) to exhaust gas flow, such that the exhaust gas pressure at the latter point is substantially constant during engine operation, and; an EGR throttle (44) rigidly connected at (46) for movement with the main throttle (14), the EGR throttle (44) having a similar geometry to the main throttle (14) such that the flow cross sections of the main throttle (14) and the EGR throttle (44) are in a fixed predetermined ratio to one another for all positions of the main throttle (14).