"When you have eliminated the impossible," Sherlock Holmes told Dr Watson "hatever remains, however improbable, must be the truth."

Applying the same logic to the political reform situation in Hong Kong, it is now possible to deduce the next step and the final outcome.

The Democratic Alliance for the Betterment and Progress of Hong Kong (DAB) will be deployed to hammer out a compromise deal with moderate members of the pan democratic camp, and hand it over to the governments involved on a platter.

How can we be so confident in predicting the way forward and the outcome? Elementary! The alternatives are all out of the question.

It is impossible for there not to be significant progress in constitutional development in 2016 and 2017 for the Legislative Council and Chief Executive elections respectively. Top mainland leaders have publically promised it. The mood in the community, freshly stiffened by memories of June 4, will not stand for anything less. Failure to deliver would mean a final breakdown of relations between the government and the public at large with potentially devastating consequences for social order and the economy. Hong Kong would become ungovernable and this cannot be allowed.

It is impossible for the democrats to get there on their own. For one thing they don’t have the votes, and for another they are now hopelessly split. Occupy Central was never a particularly good idea and anyway the movement has been hijacked by extreme groups who one suspects are determined that there not be any deal at all because their entire raison d’etre is protest. Hence they plan to invite the public later this month to choose between three alternatives, none of which are viable, all moderate reform proposals having been left off the agenda.

The ineffectual leadership has had to resort to begging people to vote in the referendum anyway to "send a message to Beijing". There is no need to worry, Beijing has already got the message as have the rest of us: you don’t have a clue what you are doing.

It is simply not possible for the local administration to broker a deal. I do not for one moment doubt the sincerity of our Chief Secretary, Secretary for Justice and minister for Constitutional and Mainland Affairs. But the fact of the matter is, whether fairly or unfairly, the government has a credibility problem.

Even if it wished to reach an accommodation with the pan democratic camp (and there is some doubt as to whether it has the nerve to even try) there is no guarantee the government could strong arm the DAB into supporting it. Conversely, if the government were to reach a tentative agreement with the DAB first, the pan democrats would probably refuse to talk at all and after a highly publicized walkout would stalk off into the sunset. Such a course pretty much guarantees an impasse.

Last time round in 2010 the central government did negotiate with the Democratic Party and the two sides reached a sensible compromise which produced tangible results. However the DP suffered such a pummeling in the media and subsequent elections from their fellow pan democrats that no party will take the risk of following the same course this time. Moreover the central government will probably want to keep the process at arm’s length for safety’s sake. It is just not possible.

Having thus far eliminated all the impossible options, we are left only with one fairly unlikely possibility. A mutual reaching out across the LegCo aisle to come up with a practicable formula that can attract the necessary 47 votes to be implemented. The leadership of the DAB – personalities like Tam Yiu Chung, Jasper Tsang, Chan Yuen Han (Starry Lee, being on Exco, will probably be kept in reserve for the final phase) – will have to sit down with the Democratic Party, the Civic Party and the Labour Party and hammer out a deal. As a gesture, People Power and the League of Social Democrats should be invited to join, but they probably won’t agree and even if they do will soon drop out or be expelled. Interestingly, Ms Chan has recently reminisced publically about a time when civilized dealings between political rivals were possible.

Both sides will have to make uncomfortable compromises, but that is the nature of the game in politics for adults.

My fellow detectives, we can hang up our deerstalkers and put the pipe back in the rack. We’ve solved the case.