Last Tuesday morning I was driving to work. I live in rural Nottinghamshire & the first part of my journey is along single track roads bordered on both sides by fields. It was about 7.10am. A lovely, sunny day, Clear & bright. I could hear the the birds singing. I glanced up & in the sky in front of me I saw an aircraft. I don't know which type it was, it was green & looked like a WW/1/WW2 plane. It flew very low across my path. It was so low I could see the pilot's face. He had one of those little leather hats on, pilots used to wear (might still do, I don't know). But, here's the thing, it was completely silent!
If it had been someone flying a plane practising for an airshow etc surely I would have been able to hear it's engine? An old plane would have been really noisy, especially being flown so low. I don't think planes are allowed to fly that low nowadays either.