Ladies Drinks - Wednesday 28th November, The Pembury E8 1JH

^ I haven't had a problem round there but it's a good point. According to the Royal Parks website:

"St. James's Park and The Mall restrictions and closures

• Monday 1 May to Sunday 13 June - The Mall (West of Marlborough Gate) plus Constitution Hill and Queen Victoria Memorial are closed to traffic **with diversions in place for cyclists. **
  
• Sunday 13 May to Wednesday 13 June - reduced access to watch Changing the Guard due to building of seating in front of Buckingham Palace and the stage around the Queen Victoria Memorial.
  
• Monday 14 May to Friday 15 June - restricted access within the Park and outside Buckingham Palace. There will be signage placed around the parks and surrounding roads to advise the public and motorists of any impact on their journeys.
  
• Monday 21 May to Saturday 9 June - Birdcage Walk eastbound and Spur Road are closed.
  
• From 1 June and over the Diamond Jubilee weekend - all St. James's Park roads will be closed for ceremonies and the Diamond Jubilee activities."
  
  

I reckon it'll be fine for us to carefully cycle in to the park but I'll try to find out for sure.