Heard a similar exchange yesterday going through Waddington zone on my way to Sturgate. Pilot called up and was told to standby several minutes later no response so the pilot called again and was given a curt response that he was told to standby.
There does need to be better communication and a faster return to pilots on standby.
I go through East Midlands on almost a daily basis and it is rare for me to wait more than a minute after a "standby I will call you back". It is also very rare for me to be refused a transit, they will usually tell me to continue on track while they work me through.
Perhaps a bit of commanality could help?