Wait a minute before you start digging the hole. If you were going to take advantage of that beautiful pit and maybe wire a PC and monitor into it - would you rather fly lain back in that Martin-Baker, or hanging against the straps looking down at the daffodils?
Of course you could just grab an angle-grinder and cut off the pertinent part, destination attic or basement, and then plant the now-noseless end into the lawn. Conversation piece and functional fun, that 30k is sounding more and more like a bargain.
Best of all, when the council come to complain you can just shrug your shoulders and blame it on the Luftwaffe