Carpediem:
I apologise in advance for not having read all relevant posts yet
I always like those who have no time to read but want immediate answers,and now it includes future lawyers !
The answer to your question is simple and was already given to you : ICAO PANS-OPS Doc 8168 : this is the bible that set the world standard and its current version says :
" Pilots shall follow the RA even if there is a conflict between the RA and an ATC instruction to manoeuver "
Now all the rest of the world regulations ( like the UK CAP, which , you are correct only applies in the UK ) and all airlines SOPs should reflect that standard. They might use other words , translations, etc,.. but that is the standard.
Please stay away from Wikipedia and other source of info, we are not at school making a project .
Airmen :
I have been installing and testing TCAS on several aircrafts and have to say that position accuracy is really not precise on the display, therefore follow the ATC instructions first and if there is a RA command then follow the TCAS vertical manoeuver!
Caution not to mix up ACAS displays azimuth resolutions and RAs. That was not the question asked and your answer can confuse the non-initiated. Once an RA has started , the position Display is useless , Pilot concentraton should be on the VSI , not on the position display.
Before an RA , ( and that includes during a TA , pilots should indeed follow ATC instructions , but once the RA has started, pilots should follow the RA, even if it contradicts the latest ATC instruction.
That partially explains why still today only 70% of the RAs are correctly followed , 20% are ignored and worse, in 10% of the cases pilots still choose to manoeuver opposite to the RA.
The other part of the explanation as to why this is still the case were/are discussed here.