Instead of attacking Pearl Harbour, Japan avoids the United States and quickly gobbles up all the avilable British, French, and Dutch territory, before concluding an armistice with those three countries in lieu of further attacks against them. This takes place in 1943.
Fast forward to 1947. The United States has entered the war and both Germany and Italy are defeated, with France occupied by the U.S.S.R. in it's eastern sections, and the Allies in the western sections. The British now want their captured territory back, and is willing to take it by force.
Britian, backed by the United States financially and economically, heads to the Far East. In the four years that Japan has the occupied territory, the islands are well foritied, and the Japanese have been building up and waiting for this moment.
First, a look at what each respective power can bring to the table, beginning with their naval forces:
Britian - depending on war losses to Japan, I expect Britian will be able to bring four Indomitable type carriers, as well as, depending on when they comission, two to four Eagle class carriers. I don't think any of the Malta class would be in comission by this time. The Colossus class would all be avilable, as well as plenty of CVEs for convoy work.
As for battleships, Vanguard would be in comission and avilable at this time. We also have the four KGV classes, as well as Richelieu, and Vittorio Veneto. Add in possibly Renown as well. I don't think any of the older QE, R, or Nelson classes would be used. QE class perhaps used for shore bombardement during amphibious campaigns.
As for cruisers, the remaining Norfolk type heavies, with plenty of CLs avilable even after huge war losses. I would expect perhaps in the neighborhood of eight heavy cruisers, twenty light cruisers, and seventy two destroyers to be deployed with the main fleet. Add in another ten light cruisers, twenty destroyers, and fifty destroyer-escorts for convoy duties.
As for aircraft, both Halifax and Lancaster heavy bombers will be avilable, along with American supplied B-17s (although I don't think they would lend their B-29s). American carrier aircraft would be supplied, depending on what is new at this time period. Jet fighters and bombers for the Eagle class CVs, advanced prop engine planes for the smaller carriers.
Japan - depending on war losses to Britian, and the aging of the carrier fleet, I expect Japan to able to field the two Hiryus, the two Shokakus, along with Taiho, the two improved Taihos, and the first six Unryus. I don't think Japan will have any trouble being able to come up with these carriers by this time period. As for Light carriers, the two Junyos, plus the two Chitoses, the two Zuihos, and I think that should be it for CVLs. CVEs, Japan could have any number of these in comission, probably somewhere around ten to fifteen will be in comission.
Battleships, the three Yamatos will be avilable, not sure about the other ships due to aging. The Kongo class, the Nagatos, and the Ises will probably see service. The Fuso class I think would be withdrawn by this time.
Cruisers, the Aoba class and some of the older CLs would be withdrawn. At the least, Japan should be able to field fourteen modern heavy cruisers, with perhaps more being constructed. In the CL department, the six Aganos would be completed by this time, and both of the Oyodos would be as well. Assuming another class of six CLs would be built to replace the older ones, Japan should be able to field fourteen modern CLs.
Destroyers, the fleet destroyers should all be completed by this time period. Japan should be able to field one hundred modern destroyers, easily. As for DEs, depending on how much the war with Britian and France impacted them will determine what they have. At the very least, from 1942 onwards, a program of 20 DEs a year should have been implement. Assuming that this is the case, Japan will have at least 100 DEs avilable for escort duty.
As for aircaft, Japan will probably have some jet fighters in service, and their carrier aircraft will have at least been upgraded to including the A7M Zekes, the B7A Ryusei, and the B6N Jills. As for land based aircraft, the G4Ms will be in wide service, meaning their aircraft won't flame down as easily.
From the naval standpoint, things could be very interesting indeed.
From the army standpoint, well Britian will be able to field a good army with modern weapons supplied by the United States, perhaps including atomic weapons, although I doubt this very much. But overall I expect the British to edge the Japanese in terms of land forces.
As for how the war will go, I expect the British will be able to reclaim some of their lost territory, but in the end the British people and the Japanese end the war with Japan holding onto a good bit of their conquered territory, probably around 1950 or so is when the war will end.
