Willie has said what I was going to. The dust, I fear, is not on your lens, it is on the sensor and there is quite a lot to be this visible, even at f14. Try shooting a white wall or clear blue sky, correctly exposed, at f22. Then blow up the frame. You will see the sensor dust then.
If you clean the sensor yourself, be very careful, or you have a ruined camera. I use the Article Butterfly anti static brush tool. Better have itdone professionally. Then try and restrict dust access. Never leave the camera more than seconds without a lens or body cap.
Change lenses as quickly as possible. Keep the camera body pointing down and try not to change lenses in dusty and/or windy environment . prevention is always best.
In this shot, you needed the Spitfire rather larger in frame. Should have been at full zoom and f would be easily enough givinfpg a faster shutter speed to avoid blur. Depth of field is not an issue here.
Problem with faster shutter speed, though, is a frozen propeller!