With the discovery of Ra's cache of known Goa'uld Stargate address's by Tolkien the British Empire slowly began to realize how truly vast the Stargate network was and the resources that they could take. On the other hand, many of the more pessimistic members of the British government and large parts of the opposition pointed out that the enemies of the Empire could potentially throw against them. The British government officially decided that due to both the importance and extant of the Stargate network that they would officially from a new military force to coordinate and command the new Imperial Interstellar Exploratory Teams. Thus, the Royal Stargate Command as a branch of the British Army was officially founded on the 15th of May 1925 with the first IIET under Captain Tolkien currently on Abydos protecting the archaeologists copying down the Stargate address's that he had found.
The official purpose of the Royal Stargate Command was to scout out worlds and determine of they could be allied with or if they were enemies of the empire and needed to be crushed by the British Army. Their secondary purpose was to secure anything of technological, cultural, military, and economic value for use by the British Empire against the their enemies no matter where they lurked among the stars. The second IIET was officially formed under one Captain Archibald Smith and tasked with their first mission to head through the Stargate to the world of Nelson and scout out the use it could have to the United Kingdom and if the British Empire could and should conquer the planet.
The world of Nelson was an ocean planet under the control of a minor Goa'uld called Astłik. She had offended Ra several times and many assumed that she was on the verge of being exterminated by Ra or one of his underlings. To counter this the majority of Astłik's few scattered Jaffa and defences were gathered around the Stargate and her pyramid. When the gate opened, and IIET-2 charged out they found that they were surrounded by a small force of Jaffa. IIET-2 sent through the radio code that requested more men and aid. The heavy guns of IIET-2 charged through the gate all guns blazing the majority of Astłik's Jaffa were wiped out in the initial engagement and the pyramid fell quickly mainly since she fled it with her First Prime aboard an old crumbling Al'kesh.
As the Al'kesh fled from the pyramid the last of the batteries died and the ship slammed into the ocean of Nelson at several hundred kilometres an hour. The corpse of Astłik washed ashore three weeks later as the world was officially integrated into the British Empire as the colony of Nelson. While all of the important technology and immediate technological potential gains to the empire had been lost the Conquest of Nelson represented the first death of Goa'uld to a human in recorded history. While not celebrated at the time it was a vital victory for the British Empire.
-Extract from Christopher Bowes's book Wolves of the Stars: A history of Royal Stargate Command
The castle of New Avondale was still being thoroughly searched even as late as 1933 due to the amount of technology that had been left behind when Ra had been thrown off the planet by the Nox, Furlings and Asgard. The arguably most important discovery was of a deactivated Asgard device meant to monitor the technological level of the planet. The device was unnoticed at first as the dark stone had been placed in the furthest corner of the castle from the Stargate. Thus, when a young child stumbled on it most of the scientists and soldiers in New Avondale thought that it was just a stone carved with a Norse rune. Until a very drunk scientist accidently turned the device on. It scanned the entire planet quickly and sent a vital message to the Asgard home world of Hala.
When the High Council of the Asgard received the message, they ordered that Commander Thor move to check on the planet Heliopolis that the British call New Windsor. The Biliskner at the time had just blunted a major Replicator offensive and Thor welcomed the brief change. As he departed the Othala galaxy he had no idea of the benefit to his people that this voyage would have in the long run. As he tore from Hyperspace above New Windsor and made sure that the worlds inhabitants and technology was not Goa'uld. Though some of it was using Goa'uld technology the majority of it was independently developed.
As the Biliskner descend through the sky the British knew that there was nothing they could do and sent a primitive radio communication requesting that the commander of the vessel come out and meet them in a parley. Thor would beam down in front of New Avondale while the senior most representative of the British government on the planet led the welcoming committee. The Duke of Gloucester had been touring New Windsor at the time and was called from Balfour to New Avondale to meet with Thor. The initial meeting was fairly brief explaining how the British had made it to New Windsor and what they were doing in the galaxy. Thor revealed little in the first meeting save that Apophis was part of the Goa'uld Empire how vast the Goa'uld empire was the technology that Apophis would have available to him such as Ha'taks and the worlds under the Protected Planets treaty.
When Thor returned to Hala he told the High Council of the Asgard that the people that had settled New Windsor were descendants of the Ancients and posed no threat to them at the current time. They were waging a war against the Goa'uld Empire and were advancing rapidly technologically but were still not advanced enough to threaten the Asgard. The final piece of advice that Thor gave was that he believed the forces of the United Kingdom of Great Britain and Ireland could form valuable allies to the Asgard in the Milky Way and that the Asgard could directly benefit by weakening the Goa'uld and empowering the forces of the Ancients descendants.
-Extract from Magni's book The Treaty of New Windsor and the events leading up to it from the Asgard perspective.
The reaction to Thor's arrival on New Windsor and abrupt departure in the British government was absolute pandemonium the Duke of Gloucester was dragged into meeting after meeting so every last morsel of information could be taken from him. After the initial chaos had died down the government turned to what they could do with the new information. The revelation that Apophis was a member of the Goa'uld Empire instead of a leader of an independent empire worried the Imperial High Command nearly as much as the news that the Goa'uld had Ha'taks that could crush their forces on Ùr Albion easily.
The decision was made the British would withdraw from Ùr Albion for now and transition to a more hit and run style of warfare against the Goa'uld and Apophis. The worlds that they did occupy would have strong defences designed to counter attacks from the air to hopefully allow the British to take out the Ha'tak. The withdrawal from worlds that they occupied would not leave them defenceless the British would leave the native people of the world weapons that could hopefully kill the attacking Jaffa and teach them how to wage a guerrilla war against the Goa'uld. Thus, as the Royal Scots marched through the Stargate to supplement the defences of Nelson they left behind a world that was ready to fight.
-Extract from Fredrick Augustus VI of Saxony's book the war of Ùr Albion