Daniel and Kingmaker:
I also specialise in this field and understand and empathise with you both.
My understanding from reading the Inspectors Manual at IM1635 is that the Inspector will submit the form DOM1 directly to the HMRC's Centre for Non-Residents for a ruling.
This interpretation was supported by the answers to Questions 1 and 2 on the Frequently Asked Questions section of the Centre for Non-Residents pages at the HMRC website
http://www.hmrc.gov.uk/cnr/resdom.htm
This view is also supported by Tax Bulletin Issue 29.
HMRC will indeed not give a ruling unless there is tax involved. However one does not ever recommend filing a return claiming non-domicile status without the Revenue first giving a domicile ruling if this is possible given that they do not charge for this generous (and non-statutory) service.
Of course - and I agree with you both - filing the claim should best be done with professional advice. Once you have the comfort factor of a Revenue ruling plus, if appropriate, an opinion then this may indeed assist in handling the death estate.
So one of things that Gerry needs in place are Wills drawn up under the laws of one of the provinces in Canada. He also needs to consider probate minimisation such as Canadian trusts, as well as excluded property trusts to minimise UK IHT when Gordon Brown changes the rules (as he may do in the parliament). All of these items do indeed need a lawyers advice...
Blessed are the peacemakers (or indeed cheesemakers if you follow the Life of Brian)