On my next trip to London I intend to visit the Brunel Engine House in Rotherhithe. Mark Brunel built the first underwater tunnel in the world - under the Thames obviously.

Mark and his son, Isambard Kingdom Brunel, are two of Britain's greatest engineers. Among other things they were responsible for SS Great Britain, Clifton suspension bridge, Great Western Railway, SS Great Eastern (carried the cable for first transatlantic telephone/telegraph) and, in the US, a canal between Lake Champlain and the Hudson.

Is your dad going? :)
I would love to take a Garden Tour..just a few houses, I am never take tours and hate riding in buses but I want to go to some of the Great Gardens of England.
How lovely to be able to see London/England at a leisurely pace with no typical tourist agendas..
I hope you will tell us all about it when you return~

Just to add to #5 in flanneruk's splendid list... Ben Haines's lecture list is continually kept up to date, and the latest version can always be found here:

victorianresearch.org/lectures.html

Cuttle

Here's another idea, for the amateur foodie in you (we're trying this on our next London trip). Find a different nationality of food to eat at each day. Pakistani, southern Greek, Russian, northern Italian, Armenian, Thai, the possibilities are endless in a city such as London. Tour the world in your stomach! :)

I've not been as fortunate as you to be able to visit London "umpteen" times but I have been there four times. The nice thing about return visits is the opportunity to see the less famous sites that we didn't have time for the first and second time around. What time of year will you be there? If it's late summer you can visit the inside of Buckingham Palace and Clarence House which are only open when the royal family is in Scotland. Also have you been to the famous markets in London - Portobello Road, Camden Lock, Petticoat Lane? We also took a boat ride on Regents Canal which was fun. Also - the Banqueting House, Spencer House, Inner Temple Church, HMS Belfast, St. Paul's Church (aka The Actors Church, at Covent Garden) and Syon House (across the river from Kew Gardens) are all worth visiting.

I'm also planning on returning in 2006 (my 2005 vacation time is already committed elsewhere) and my "wish list" for this trip includes:
Abbey Road (If you are/were a Beatles fan, have your picture taken crossing the famous zebra corssing)
Art sales along Bayswater Road on Sunday mornings
Speakers corner (also on Sunday)
Monthly book fair at the Hotel Russell
Princess Diana memorial fountain in Hyde Park
Cabinet War Rooms
Boat ride on the Thames - last time we did Westminster to Greenich, next time we'd like to go the other way - Westminster to Hampton Court.

Other day trips outside London that I've enjoyed that you didn't mention having been to include:
Battle (site of the Battle of Hastings)
Brighton (fabulous opulent Royal Pavilion built by George IV while Prince Regent)
Winchester
Stonhenge & Salisbury
Canterbury
Warwick
York
I've visited all the the above by train & bus - I've never driven in the UK either.

I don;t think yo'll havbe any trouble filling up 12 dyas with interesting things to do!

Thanks for all the suggestions!

Scarlett,
Of course my dad is going, it is the only way I can afford it :). This year it has taken us along time to find an exchange.

Daisy54,
An ex boyfriend was the reason for so many trips to London, not the best of reasons!

Another fun and different thing to do in London is to go to a car boot sale. If you like garage sales and flea markets, you'll enjoy it.

There is one on Saturdays, 11 - 3 at St. Augustine's School in Kilburn Park (Bakerloo line - Kilburn Park station.) It's just a short walk from the station to the school. :)

We booked it today!!! We will keep you informed of our travels!

Thanks all, I am on my way.
flanneruk a big thanks to you, I will email you personally to thank you as soon as I get to the UK.