https://en.wikipedia.org/wiki/Double_Irish_arrangement
At the time, customers had no idea that this was why these tech companies were operating out of Ireland. All they knew was that you got a lot for your money, and, more importantly, the latest tech. However, you might have to wait 28 days for delivery. It was important to the business model that Dell had not one single employee in the UK or other EU countries apart from Ireland, so it was call centre for everything before the web came along.
There may have been more to the Dell business model of customisation. In the UK, if you order a bespoke product, then you don't have the normal rights to just return it if you don't like it, you are stuck with it, and at the mercy of customer service.
I don't know if Dell played this card because they always had that refurbished gig going, where you could get good kit with a few dents and scratches. Nonetheless, there was very little manufacturing going on, it was just a screwdriver operation, final assembly of what amounted to knock-down kits. You did get the latest and greatest though,
Regardless, compare with the original IBM model where they made PCs in Greenock, Scotland. Undoubtedly you know more about this than I do. However, as I understand it, the original Scottish factory made typewriters before the PC came along, and IBM were incentivised to choose Scotland in the post war years, when the British government were quite serious about bringing industry to Scotland. Shipbuilding had gone on the Clyde, and with it steel and the outfitting and everything else that goes with shipbuilding. There was also an emotional reason for Greenock, Watson had Scottish ancestry.
The product that came out of Greenock was really good. To this day people want those keyboards that came out of there. The Trinitron monitors came from Sony's plant in Bridgend Wales, which they originally opened in the 1970s to make TVs, again with the usual government incentives. Sony also supplied Dell and Gateway 2000. Now all that has gone, RIP Trinitron, we loved you...
I am sure there was more to the supply chain, since, in period, semiconductors were made in Silicon Glen. However, these tended to be things like DRAM chips, where vast fortunes would be spent building a fab for it to be pretty much stillborn.
I am curious as to how 'vertically integrated' the IBM operation was, since hard disks were also made by IBM in Scotland. The IBM PC story is told as 'using commodity off the shelf parts', but IBM PCs were not a product of a screwdriver operation.
It is shocking that the UK have done so badly at tech. However, how was IBM supposed to compete against those tax fiddlers operating out of Dublin? Why did the EU allow Ireland in the UK when they were not taxing the big corporations? The Irish shot themselves in the foot with this as they ended up with house price inflation and very high personal taxation.
The UK also had a lot of tech in the M4 corridor, this being the motorway out of London that goes all the way to (drumroll...) Bridgend. Reading was the prime spot with Compaq, SGI, Microsoft, Oracle, Sybase and plenty of others setting up shop there.
In Reading there was an industrial estate that housed most of them, with their own private motorway. If you were on the train going past you imagined this as being a full on mini-Silicon-Valley, however, not a lot was going on in those impressive headquarter buildings. I am sure Sybase was just a couple of guys hassling the few customers they had for whatever license fees they could get from them, as for Microsoft, there was nobody writing code there, you just had product managers for things such as Microsoft Golf. Same with SGI, just a very big building with nobody in there. It all looked impressive from the train, however, it was just a Potemkin Village.
I am in genuine disbelief regarding how the UK messed up with tech given the advantages of a reasonably educated population, a reasonably high standard of English, access to the EU market, access to the former colonies, an army of 8-bit coders (from the BBC Micro project) and access to capital (London).