J.R LaFleur & Son were an instrument maker founded in London in 1862 who were acquired by Boosey & Co in 1917. Boosey merged with Riviere & Hawkes in 1930 to become Boosey & Hawkes. LaFleur was maintained as a separate company until the 1930's. Then the brand name was "retired".
Sometime in the 1960's Boosey & Hawkes had the opportunity to buy in budget priced instruments from Eastern Europe - mainly from VMI of the GDR (East Germany) and later Amati of Czechoslovakia.
VMI was based in Markneukirchen and is now known as B&S. This was a collective of factories under communist control making all sorts of brass and woodwind instruments. The people making them were German Speaking Czechs from the Sudetenland who had fled the Russian occupation which happened at the end of the second world war. After they left, the Czech authorities re-established production in collectivised factories using the old names (Amati and Cerveny).
By the 60s, VMI in Markneukirchen was manufacturing student level instruments under the "Weltklang" brand (German for "world sound"). Boosey and Hawkes thought this sounded too Germanic and the word "klang" would make people think they sounded bad so they had them engraved as "La Fleur by Boosey & Hawkes". The same instruments were also imported by Barnes & Mullins Ltd and branded as "B&M Champion". I saw these for sale in an Edinburgh music shop as late as 1994, which must have been old stock. The same instruments were also sold under the Weltklang name by people importing them directly or who had obtained them from bands visiting East Germany who were often part-paid in instruments they could then sell on (Kenny Ball had this arrangement with the East German authorities and mentions it in his autobiography).
From the 70's through to the 90's Boosey & Hawkes moved to obtaining instruments from Amati in Czechoslovakia. Some of them have "LaFleur" engraved on them, but most say "Corton". Then in the 90's Boosey & Hawkes started calling these instruments "Boosey & Hawkes 400 Series". To confuse matters, some of the 400 series instruments were actually made in the USA.
By the late 90's Eastern Europe had collapsed and there was no more subsidised production to earn foreign currency. Boosey & Hawkes decided to establish their own factory in India using tooling from some of their previous ranges of British made instruments. Indian production of the 1000 series trumpet and cornet replaced the previous East European models.
As to quality, well these are sturdily built instruments. Generally the intonation on the trumpets, cornets and flugels are OK. They are as good as the current cheap Chinese ones, and in some ways better as they are more easily repairable and the sturdier construction makes serious damage less likely. It is a question of trying out an instrument and seeing if they are any good. The cheapest trumpet I ever bought was one that turned out to be a Weltklang stencil which I bought recently for £23. It turned out to be OK (video).