Remembering the last time I traveled to the UK, I recall most things seem to be priced on that £=$ ratio (I was shopping for music CDs at the time).
Given the 20% VAT and duty (whatever that number may be - I couldn’t find a source for an actual percentage), that may more than make up for the difference in the exchange rate. (Currently £1 ≅ $1.22).
You mean when £1 was worth around $1.75 or so? Yeah, stores were still charging the £=$ ratio for imported goods, which made it worth importing the item yourself and paying duty/VAT - it still wouldn’t make up the difference.
I was a ‘vinyl head’ until the mid-2000’s when most of the industry obviously moved to non-physical distribution being king, and I moved on (and grew-up somewhat, as being into and spending too much money on music became untenable due to the usual life events).
I’d often import from the US to UK bulk orders between the mid-1990’s to mid-2000’s, as buying direct in UK was more expensive even after shipping costs (and import controls were significantly more lax on certain shipping services, so often weren’t collected!).
Around that time, I also remember lots of holidaying TV shows would extol the virtues of enjoying trips to NYC and other US city destinations, and the cost savings of buying branded goods, while not hitting import tax limits.
Those were the days… but not really as much of a thing now, lol!
There are other financial considerations. If you buy the device with a credit/debit card issued by (most) British banks, you have to include: a) the mark up on the exchange rate applied and/or b) any foreign purchase fee (usually around 3%)
There are some financial institutions that provide payment options with forex rates closer to the “market” exchange rate and with small or no foreign purchase fee, but then you’ll need to check your current cards and which others you could get before your trip.
Nevertheless, I did exactly that in 2017, I was able to order before my trip (with a UK keyboard and an “international” charger adapter set), asked Apple for the MBP to be delivered to a friend’s house and paid with a US issued credit card. Overall, I saved around 10% compared to the UK cost.
An important consideration is that Apple’s waranty (at least for laptops) is valid worldwide.
So, do your maths, considering US sales taxes (if applicable), credit card fees and forex markups and a charger with UK plugs.