I know this thread is quite old, but in case anyone else plans on flying here, see info below. This is what I did and flew today with their permission. They did ask me for a copy of my drone insurance, which I provided. I have also provided them with copies of the photos that I took.
You can request permission to fly your drone at Broadway Tower in advance, by emailing office@broadwaytower.co.uk. This information is also on their website:
Drones and Filming
Broadway Tower is a small celebrity in the film and media world. It has played supporting roles to international stars and film characters and featured on our much-loved British TV productions. Filming or use of drones at Broadway Tower requires prior permission; please submit details of your request to us at least 7 days prior.
Please contact the office for more information: office@broadwaytower.co.uk
Please note visitors filming without consent will be asked to vacate the premises and will be liable for any claims in relation to public liability and damages to livestock or buildings.
I hope that helps someone 