capital gains tax

I am a UK NRA married to a US citizen.  I was once a green card holder, but properly renounced this way before 2000.  But we retained a joint Mutual Fund account in the US which we are clearing out to remove problematic items such as non-HMRC reporting funds.  This will yield capital gains.  MY US citizen wife will be taxable on this.  But will I ?

Looking at the US/UK DTA article 13 on Capital Gains, Article 5 says "5. Gains from the alienation of any property other than property referred to in the preceding paragraphs (real property as defined in te treaty) of this Article shall be taxable only in the Contracting State of which the alienator is a resident."  The property referred to here includes, I believe, shares of Mutual Funds and corporations and similar investments registered in the US.  The first interpretation would be that the gains are taxable to me (NRA) only in the UK since it is the Contracting State in which I am resident.

If gains are taxable to me, what is the treaty rate applicable, since gains are no particulat rate cited, nor in the Tables of Pub 901.  And can we split the gain and be taxable on half each ?

If you both UK resident and are subject to UK tax on the arising basis, the UK has the primary right to charge tax. UK tax will be under the OIG rules, so your cost is a pool cost (calculated using historic spot exchange rates). Your spousal share of ownership will be determined by local law where the investment is held.

If you are a non-resident alien, the tax treaty is not a relevant question as there is no US tax on your share of any gains at all.

guya - you say "If you are a non-resident alien, the tax treaty is not a relevant question as there is no US tax on your share of any gains at all."  Since I share some US registered Mutual Funds with my spouse, I imagined there would be US Capital Gains tax on that, but I've come to the same conclusion, though I can't actually find it written anywhere.
The situation of an NRA is very little discussed on this site, but I suspect that a lot of people are NRAs, being owners of US property (real estate), retirement savings or simply sharers of family investments like me.  I only discovered this year that as an NRA I have to fill in the Schedules NEC and OI that go with the 1040nr, and that I do not get any of the exclusions or personal exemption.  Will I have to fill in these schedules every year - nowhere does it say that if you did it last year, there is no need to repeat all that guff about not being a tax cheat all over again.  On the other hand, my capital gains in the US seem to be US tax-free, including capital gains dividends as specifically stated on the 1040nr instructions.

I would add as a general comment, that althought the US tax system is an absolute pain in the proverbial, if you read the instructions carefully and completely, a lot of things become clear.  For example, what forms you have to follow, as asked by a poster a few post above me, becomes clear if you just do what it says.  Like - 'if you are a this and are married to a that, then do not enter your amount here, but fill in form XXXX and enter the result on line 47 of the worksheet hidden on the page 87 of form 1091nr instructions, then enter the result on line 1029h of Form 902 and line 66 of 1040nr.  Take away the number you first thought of and send in the money.'