Could it be New Rail Alphabet by Margaret Calvert/Henrik Kubel?
Do you know who designed the book?

(Edited) No I don't think it is.

Not Helvetica. The "n" curve is too uncompensated, the "a" bowl too straight at the top, the middle of the "s" too horizontal.

Edit: This was a reply to a now edited speculation that the sample may be Helvetica.

Is this another attempt from you for Unica Haas?

No attempt for Unica Haas ...
i know it’s not Helvetica ... I guess 1985 is prob right, just had a look at the site.
It was designed by Cartlidge Levene ..

Thanks for help!

It's not Haas Unica either, the a in that alphabet is much curvier. It reminds me most of old British Rail signage and little known 'Airport' typeface (pretty much the same thing, I think).

http://en.wikipedia.org/wiki/Rail_Alphabet

The s is the giveaway character.

http://www.newrailalphabet.co.uk/

Here is some more information on the digital version, which I think differs quite a bit, though it is in a sense official as it was revised by it's author.

I hope Barbican is Gold Foil.

Do I get my gold star now?

Yes, you can. Sorry for the delayed award ceremony!

Thanks Florian!