The British Pacific Fleet (or BPF) can be looked at a couple of different ways. The idealist will see it as Britain's attempt to help out in the Pacific the way the US did in Europe. The more politically minded see it as Britain's last chance to regain some of her overseas possessions (Hong Kong and Singapore in particular). The cynic views the BPF as Britain's chance to get a seat at the winner's table in the Pacific... a table that, to be blunt, the US owned. Along with the all the chairs and the room the party would be held in.

In truth, all three of these views are correct in some way, and it very nearly didn't happen at all. When the Royal Navy put forth the concept of a British task force fighting alongside the US Navy, Admiral Ernest King, Chief of Naval Operations and Commander-in-Chief US Fleet and a man with a long-standing dislike of the British, refused it out of hand. It took the intervention of FDR himself to change King's mind, and even then it came with stipulations.

Primary among them was that the BPF had to be self-sufficient. The logistics train for the US Navy was stretched too long as it was, so the RN had to fuel and feed herself. This is the most brilliant part of the BPF story; from a dead stop early in 1944 to early 1945, the Royal Navy created their own logistical network from scratch.

To be sure, there was plenty of consultation with the US Navy on how to do such a thing, but beyond that the RN managed it on their own, mostly. The fleet would be based in Australia, but the speed of which the war was progressing caught everybody flat-footed. It was realized soon enough that Australia was too far from the soon-to-be battlegrounds of the Japanese Home Islands and their vicinity. A forward base at Manus, north of New Guinea, was constructed with American help, which eventually became known as "Scapa Flow with bloody palm trees."

Food and fuel was provided via underway replenishment. This turned out to be something of a nightmare, as the Royal Navy had no real history of such activities. After all, there's not a lot of need for such things in the Med, or off Europe... the scale of the Pacific can be mind-boggling. What tankers they had were too slow and used the over-the-stern method of refueling. This is safer, but slower, than the US Navy's method of running ships alongside the tanker. This put great stress on the refueling capabilities of the RN... fortunately, "self-sufficient" was usually interpreted by the US Navy to mean "you can't have any of our ice cream, but our fuel ships are right there, feel free."

With ship repairs, food, and fuel accounted for, the next problem that had to be tackled by the BPF was aircraft. Battleships and cruisers fire shells at the enemy; along that same way of thinking, aircraft carriers "fire" airplanes... and the BPF had six fleet carriers and four light carriers on the roster. The planes of the carriers had engines that would need repair or refurbishing, new planes would have to be pulled out of packing crates and constructed, electronics would need to be attuned, and so on and so forth. To accomplish the task of keeping the carriers equipped, the British came up with the concept of the "Mobile Naval Air Base," or MONAB. In theory, these were self-contained maintenance facilities that could pack up and move as needed. In practice, most of the MONABs were based in Australia, and almost all of the aircraft for the carriers went through them at one time or another.

Two REALLY mobile repair bases were HMS Unicorn and HMS Pioneer. Looking for all the world like aircraft carriers in their own right, they were depot ships, the same way submarines had support ships. They were capable of working on both British and US engines and aircraft, and could keep a steady flow of planes coming without having to go back to Australia for more.

Finally, a small fleet of nine escort carriers would ferry planes from Britain to Australia to the BPF carriers as needed.

So what about the activities of the BPF in combat?

For the most part, the BPF was given... unglamorous... tasks. While the USN went hunting what was left of the Japanese Navy and supported most of the combat in the theater, the BPF blooded themselves at Palembang, Sumatra in January of 1945.

There, they shut down one of the last Japanese oil sources at the cost of 48 aircraft. After Palembang, they would be aimed at smaller islands and bases that needed to be "stepped on", but not invaded. It wasn't until March of 1945 that they were integrated into combat ops with the US Navy as part of the invasion of Okinawa.

Whether by malice or accident, the BPF found itself in the middle of the kamikaze hornet's nest. First off of the Sakishima islands, then Formosa, the BPF spent nearly a month as a protective shield for Okinawa proper. In many ways, their carriers were well-designed for such business, as their armored flight decks were, if not invulnerable to kamikaze, at least much more resistant to such things than the wooden decks of the US carriers.

The BPF later attacked the Japanese Home Islands directly, both with carrier planes and gunfire. Indeed, King George V fired the last shots in action from a British battleship when she bombarded the naval base at Hammamatsu.

If Operation Downfall, the invasion of Japan, had taken place, the BPF would have been in the thick of it, much the way it had been at Okinawa.

At its strongest, the British Pacific Fleet had six fleet carriers, four light carriers, nine escort carriers, four battleships, 14 cruisers, 35 destroyers, 31 submarines, and a startling proliferation of smaller ships. It was easily the most powerful collection of vessels the Royal Navy had ever assembled.

The best sources I've read about the BPF are both by the author David Hobbs, CMDR, MBE, RN (ret). His two books "The British Pacific Fleet" and "Moving Bases" cover just about everything you could want to know about the formation, workup, and combat history of the Royal Navy's last big fleet. I can't recommend them enough.

(my apologies on the length of time it took to post this second part of the answer. My broadband connection died a minute or two after I posted the first part, and only now, five days later, has it been repaired.)