See the old bird can still climb like a good un ;-)
Somewhere there's a famous conversation between a Vulcan and a USAF base in the States. It consists of an initial height clearance request, which takes a little while to be granted, followed by:
"Sorry, past that already!"
"Cleared to flight level 300"
"Past that too"
"Cleared to flight level 400"
"Past that as well"