What backup policy? Even now there are loads of archive material being junked.
Well, yes, that was sort of the point. Archival is one of the things you'd think the BBC would be
good at... even though it didn't seem to originally be apparent to them, you'd think the Goon show thing would have persuaded them. They needn't even keep the original media if they can automate effective high-bitrate digitisation [1] -- but then perhaps this is what the current initiative is all about.
I don't know what the data density of 2in videotape is, but I bet that nowadays a good Sorensonning or MPEG-4ing could get three semitrailers of it onto a single winchester.
Peter
[1] And a backup strategy and a rolling programme of re-copying to newer media as old ones become obsolete.