Back in the day i lived very close to the extended centre line of 23R 5L (apologies if they were designated differently then magnetic changes etc) and I remeber the rotordyne clearly as that runway was used a lot back then with dpertures on 23 and landings on 05 it was a great spot for a kid fascinated by aviation.
As irecall the rotordyne underwent an extensive set of tests at LHR and even now 50 plus years on i can rememebr just how incredibly noisy the Rotordyne was.However it was a very very impressive looking machine at a time when BEA were still flying Daks and Vikings around as mainline aircraft .
Iwas neve sure why it got cancelled other than no one buying it but was that to do with noise, the weird appearance putting airlines off or the focus on early jets and the success of the Viscount as Europes short haul king making people feel it was just too weird.