Eventually one gets fed up with being courteous and sticking to unemotional facts. I've still to receive a reply to this one I sent:
I refer to your reference which arrived today.
I would like to thank you for a good laugh prior to Christmas. Having received previous communications from your department telling me that I am not liable to UK tax and, given the address to which you set the notice of underpayment, I assumed the notice to be some sort of joke.
However, in order to allay months and months and possibly years of frustrating communication with you trying to claw back my money because of imposed deductions from my RAF pension I thought that, just this once, I had better treat this seriously and hope that the message gets through to the spotty faced imbecile who generated this notice.
For your information (and please feel free to put this on my record - computer or otherwise), I emigrated to Australia in May 1993 and have lived here permanently ever since. I am an Australian tax payer and, as I am sure you realise, there is a double taxation agreement between the two countries. Since emigration I have not paid UK tax. I am therefore more than surprised that someone in your department thinks that I should now start. Of course, if you wish to tax me as well as the Australian Government then, as a quid pro quo, I would expect my UK State Pension which commences payment in April next year, to be increased in line with that for UK residents.
Please adjust and amend whatever records that you might have to reflect my personal situation forthwith.
Yours faithfully,