On the point of TT:120 UK stock looking small. in 2022 I travelled from Newark on Trent to Venice by train.
Four trains, LNER to London, Eurostar to Paris then an Italian Frecciarossa to Milan and a Swiss train to Venice - the latter being a through train from Geneva.
The train from Newark to King's Cross was the only one where we travelled First Class, and had the most cramped seats of any of the trains- despite the seats in UK first Class being 2+1 seats across the gangway and all of the others being 2+2. That brought it home just how much smaller the UK loading gauge is- our trains are not only much lower but also a fair bit narrower, compounded by the Azuma not being built to the full UK loading gauge to allow for tilt.
Pics show the Azuma and the Swiss unit.
Les