I don't think the Angel has been around long enough to be 'iconic'. 'Iconic' suggests that it has a special place in the national psyche.

I think Big Ben would count, although it was named after a man whose seat was in Wales (and whose wife was responsible for much of what is considered iconically Welsh).

Puffins maybe?
Roses?
Lavendar?
Crumpets? or Hovis?

siân