Many believe that this stance has been heavily influenced by homophobic religious pressure groups in the US. If this bill passes not only will life be made intolerable for gay folk in Uganda (anyone who believes we have a problem with asylum seekers* should think about the implications of this...) but it will also be a dangerous boost to the already powerful US based religious homophobic movement.
There's more about this bill on The Guardian site:
The protest will be held outside the Ugandan High Commission:
58-59 Trafalgar Square,
There's a Facebook group for the protest here: http://www.facebook.com/event.php?eid=183179992377&ref=nf
*I don't but many do.