We had two pairs of Chinooks and a Puma around us yesterday. I could not get the Chinooks on ADS-B Exchange but I did hear them. Both lots went over my son's house and he says they were at no more than 100ft. He sent me a photo, looked more like 150ft to me. The Puma was at about 250ft and came up on ADS-B.
I was nice to see (hear) the RAF operating in LFA 18 again.