Yeah I looked at doing that yesterday as I did that same trick countless times on my old Metro 1.1
but the fitting isnt the same, the rear slides about on a thinner bit of plastic on the arm, the front ones wont be able to fit, well mine won't, they are Bosch something or other.
I just rang Halfords, they do rear refills, 16", 18" and 22", and they can be cut to size.
Thing is the 16" is £6.99 anyway!
could try Wilkos but I guess I'll have to take in the current blade to match it up. Seems like a bespoke fitting.
Have you tried this jug?
Do they have rear fitting ones?
The wiperblades 'Champion' one is now £4.45 but out of stock so I have emailed them to ask when they get more in...