Tony
These rifle manufacturers don't half confuse things by keep doing different deals with different pellet manufacturers.
Crosman ( New York, USA ) have been banging out the 'Premier' style pellet for a few decades now. The 1250 in a box ones were all the rage in FT in the 90's. The boxed Prems are apparently from selected dies and they only use those dies for a certain run time. When you buy a box of 1250 Prems you are apparently getting 1250 from the same die ( the variable sizes make me doubt that these days ). Apparently when they've finished the run of Prems they use the dies for a while longer. Those used to be Crosman Accupell and you may have got mixed dies in a tin of 500. These were/are all 7.9gr pellets in 0.177. They look like they are two halves stuck together with a line down the centre and there's a tiny step at the back end of the tail. Shiny shiny pellets with a lot of infill inside the tail.
Webley then had pellets made by Crosman in New York and called them Webley Mosquito ( 7.9gr ). It said 'Made by Crosman in the USA' on the front tin label.
Webley then seemed to do a deal with JSB as the UK importer and started selling Webley Mosquito Express. These were a lighter version of the JSB Exact ( 8.44gr ) at 7.87gr. Maybe that deal expired after a while as Webley stopped selling that label and JSB were selling JSB Express at 7.87gr ( same pellet ).
Webley also seemed to take over the Accupell brand name from Crosman. Webley sold those as Webley Accupell ( Prem style 7.9gr pellets made in New York, USA by Crosman and originally Crosman Accupell ).
Webley now sell Accupell FT. These are exactly the same weight and style as the H&N FTT ( 8.64gr ). These are undoubtedly made for Webley by H&N in Germany and are basically FTT.
Daystate have done similar things. They jump from Crosman Prems ( Daystate Rangemaster Li ... 7.9gr made in USA ) to JSB Exacts ( Rangemaster Sovereign ... 8.44gr made in CZ ). Daystate do the Rangemaster Kaiser which are 8.64gr and will be made by H&N and will be FTT.