Appears it was actually Engels in a letter to Marx, but the two were much in agreement on this topic.

The business with Jones [3] is very disgusting. He has held a meeting here and spoken entirely along the lines of the new alliance. After this affair one is really almost driven to believe that the English proletarian movement in its old traditional Chartist form must perish completely before it can develop in a new, viable form. And yet one cannot foresee what this new form will look like. For the rest, it seems to me that Jones’s new move, taken in conjunction with the former more or less successful attempts at such an alliance, is really bound up with the fact that the English proletariat is actually becoming more and more bourgeois, so that this most bourgeois of all nations is apparently aiming ultimately at the possession of a bourgeois aristocracy and a bourgeois proletariat alongside the bourgeoisie. For a nation which exploits the whole world this is of course to a certain extent justifiable. The only thing that would help here would be a few thoroughly bad years, but since the gold discoveries these no longer seem so easy to come by

https://snylterstaten.dk/letter-from-engels-to-marx-manchester-7th-october-1858/