do in favour vs do in a favour

Some examples from the web:

• Ten years later, the Church in Latin America feels happy at everything it has been able to do in favour of the family.
• Dear brothers and sisters, I willingly welcome this occasion to thank you for what you do in favour of an organic and efficient pastoral service for migrants and itinerant peoples, putting your time, your competency and your experience at this service.
• One can understand, then, the care that many local communities have devoted in the past and continue to do so in favour of these centers of culture and Church action.
• For this reason, I do not intend voting in favour of this regulation.
• Therefore, during voting time tomorrow, I recommend that we do not vote in favour of them.
• That is why I would earnestly request that when the time comes you do not vote in favour of Amendment No 17.
• Thirdly, the security loopholes which people have repeatedly claimed will be created if we do not vote in favour of the interim agreement simply do not exist.
• In order for the referendum to be legally valid it was necessary not only for there to be a high turn-out, but also for over half of those entitled to vote to do so in favour of the proposals.
• Why do governments opt in favour of the new bathing water directive?
• The second reason why I have recommended that we do not vote in favour is because with regard to the free trade area, regional differences are not taken into account.
• If you do not vote in favour, then I would have to say that you are a person who makes big speeches and then does not vote accordingly.
• In this case the abovementioned tax reductions do in fact favour firms taxed in Gibraltar, in comparison with all firms active in the United Kingdom.
• For in that case he or she would, of course, not be elected, because more votes against than votes in favour do not constitute a relative majority.
• Mr President, those of you who know me will be aware that I do not usually speak in favour of public aid which distorts competition.
• Who do you favour in the Virginia Slims Tournament?
• Today, your actions do not speak in your favour.
• I do not militate in favour of not punishing guilty people, but not by using the death penalty.
• But to fail to do this in favour of the back-door approach of trying to stop the payment of money in order to indirectly force the hand of the Member States is something that I quite simply consider to be wrong and even cowardly!
• as a result, the extensive use of the margin jeopardises the Union's ability to face and to react to unforeseeable emerging crisis, and do not speak in favour of the proposed financing;
• If we do not vote in favour of the report it is because we want to indicate a preference to do business on reform now rather than later because we believe, on the evidence to date, that this Commission is a reformist Commission.

Some examples from the web:

• And they say that Henry cannot be trusted to do the deed, so, one of them has to step in and do him a favour.
• Did he ask you to do him a favour in return?
• Fourth sister has done Zhuoyun a favour.
• But as a favour to you...
• Weird to hurt someone as a favour.
• Commissaire de Kerven has asked a favour.
• I do it as a favour.
• Pattie, do me a favour.
• I suppose he owed someone a favour.
• They are doing us a favour by living there under these difficult conditions and we must return the favour.
• If not as a favour to me, a favour to yourselves.
• Now do yourself a favour, get out.
• Ushi-san, I'd like to ask you a favour.
• I need a favour, Gruber.
• I have a favour to ask you.
• Shawn, do me a favour.
• My mother sends me to ask a favour.
• So, do me a favour.
• Jorge, I have a favour to ask.
• I am doing the country a favour.