I do think it's odd (not just on this thread, but on many others) that people always assume that a "London wedding" will inevitably be a very cool, very stylish (for those in the know of what is classed as "London-stylish"), very laidback affair ...
(The same wild generalities seem to be made about Irish weddings - apparently everyone is so dressed up that the Reformation dress posted above would look low-key?!!! Not the numerous ones that I have been a guest at - & I am Irish!)
For all we know (& it's strange that hardly anyone has asked for more details of what type of wedding it will be, etc), the bride's family could be coming from Shetland & the groom's from Scarborough - & the uni friends could all be visitors to London too???
@PithyBeaker - where is the wedding, & the reception afterwards, going to be held? Is there a suggested dress code &, if not, have you any idea of how relaxed/dressy the vibe might be? And how many guests will be wearing such cutting-edge fashion that their attire will be passé by the end of the evening ...?!!!
Also, I've just realised you mentioned that dresses are often too short for you. Does that mean you prefer to wear something ankle-length? And that a short dress is out?