Hi everyone.
Apparently a nice quality production art glass Kosta vase with what looks like a legit signature. Of course, trust me to buy one with a letter code not in Jackson or Haanstra!

Facts:
Sourced from an English Midlands general dealer, so more than likely originally retailed in the UK
h. 255mm (10")
weight 1358g (3lb)
3 piece construction, neatly ground out and polished pontil mark
foot and rim neatly cut, chamfered and polished
Some wear to the base
Slate blue colour, very '60s, very Caithness
Marks: "L" or "7"; "Kosta BH 359" or "Kosta BH 353".
Any ideas on dates, interpretation of marks, designer, name of range, or anything else?
Thanks for looking, Bernard C.

ps - thumbnails average less than 1Kb, main images 13Kb, edited using IrfanView. Okay, Ivo?
pps - If you use IrfanView and you are like me, sometimes hitting the wrong key, occasionally you can find yourself with an image filling the whole screen and no way out. Try the Enter/Return key - it will get you back to normality.