But it was never an exact replica. For example, the Rohirrim in the legendarium were an upgrade to the historical Anglo-Saxons, because they had horses
That is true. However, their buildings are exactly the same (longhalls), and their culture and governmental system is also the same. Their language is also 'translated' into Old English, the language of the Anglo-Saxons -
mearas means 'horses' and Théoden means 'leader of a people' (he is addressed as 'Théoden king' rather than 'King Théoden' due to Old English grammar - one would transcribe it as '
þeoden cyning'). Even the poem 'Where now the horse and the rider?' is adapted from the Old English poem 'The Wanderer'.
For the Shire to be the Victorian Age it needs more to compare than just rolling green hills hit by a sudden industrialisation (isn't that the only thing that is similar)
There are far more similarities than that. The name 'Shire' is an obvious one, as are the other placenames in the Shire sounding very English indeed (Frogmorton, Whitfurrows, Woody End, Oatbarton etc.). There are also the various dialects, social classes (rural aristocrats like Merry and Pippin, well-to-do middle class hobbits like Bilbo and Frodo, and lower class servants like Sam), the governmental system (the powerless, hereditary 'head of state', the Thain and an elected leader, the Mayor), and so on (the Shire Post Office being another good example). Even the hobbit brothers Marcho and Blanco are directly analogous to Hengest and Horsa, legendary leaders who brought the Saxons to Britain (both sets of names are related to horses).
When it comes to the hobbits' adventure, the similarities become even more apparent - Sam's loyalty to Frodo is very similar to that of an English 'batman' (effectively a squire) to his officer, and British officers in World War One were almost entirely composed of upper and middle class men, whereas the privates were largely lower class.
Honestly, any English (or even British) person can see how incredibly English the Shire is, in the traditional sense.
Within Middle-earth there is a long list of peoples and places that had ideas from the history and geography of England. Take Tol Eressea as another example, it was to become England in an early draft. One of those terrible maps that seek to meld Middle-earth to Earth should have little Englands all over the place.
I would contend that nothing even begins to approach the Shire in terms of similarities to England. Onto the subject of maps - this is a map from the Ambarkanta:
As Middle-earth is meant to be our Earth in the distant past, you can quite easily see the similarities (the rough shape of Africa being the most obvious). Just to clear any confusion about that up:
"
...imaginatively this 'history' is supposed to take place in a period of the actual Old World of this planet."
- [The Letters of J.R.R. Tolkien, 220 (#165)]
"
I am historically minded. Middle-earth is not an imaginary world. ... The theatre of my tale is this earth, the one in which we now live, but the historical period is imaginary."
- [The Letters of J.R.R. Tolkien, 239 (#183)]
If there are such heavy cultural similarities between inhabitants of the west of Middle-earth and the Western world of our own past, we must therefore assume that strong cultural similarities exist between the Haradrim and 10th century Arabs, for example, or between the Balchoth and nomadic steppe tribes of central Asia. Some Easterlings could even be seen as coming from the Far East, given their 'sallow skin' and well-crafted armour and weaponry.