This would be even funnier if it wasn't true.
I recently signed a contract to sell our house. Because my parents are in Perth, I had to sign on their behalf. Our solicitor arranged an 'authority to sign' allowing me to do this under the Real Estate act.
When we exchanged, the purchaser's solicitor refused to accept my signature because it was not executed under a power of attorney. After much to-ing and fro-ing, he agreed to accept the signature of the Real Estate agent under a similar authority to sign.
So to summarise, he would not accept the signature of a blood relative but he would accept the signature of a real estate agent!!
Ho ho ho, hee, hee, hee.
Now isn't that the funniest thing you've ever heard?