I have been to London four times, but I'm stopping over en route to Budapest next month and will have an afternoon to putter around. I'm looking for recommendations for beautiful churches that feature ornate decorations or beautiful stained glass. I'm hoping to learn about some off the beaten path churches that I haven't visited previously. Among the ones I have visited in the past include:
Westminster Cathedral
Westminster Abbey
St. Paul's Cathedral
Southwark Cathedral
St. James Catholic Church
St. Mary Le Bow
St. Batholomew
St. Martin in the Fields
St. Brides
Temple Church
I know I've been in a few others, but can't remember their names right now.
Thanks in advance for any suggestions.

Christ Church Spitalfields While you are there, you can pop into AGold, my favourite London food shop

http://ccspitalfields.org
Website for Christ Church

While we're about it, here's the Webster for A Gold http://www.agoldshop.com

You might find the Farm Street Church interesting (located in Mayfair):
http://farmstreet.org.uk/tour.php

Aggiegirl, a few more suggestions:

ST. MARGARET’S CHURCH on the grounds of Westminster Abbey called the “parish church of the House of Commons” – site of many historical events including the marriage of Sir Winston Churchill to his beloved Clementine in 1908.

ST. CLEMENT DANES – on an island in the Strand, built by Christopher Wren in 1682, home church of the Royal Air Force. Margaret Thatcher’s funeral procession paused here in April 2013 so that her coffin could be transferred from the hearse to a gun carriage before being taken to St Paul's Cathedral.

ST. MARY LE STRAND, another lovely nearby church built around 1714, the site of Charles Dickens parents’ marriage in 1809.

For an off the beaten path church, you might like St. Dunstan in the East--it is a Wren church but heavily damaged by WWII bombs and now is a lovely lovely quiet garden spot. We had a moving visit on a drippy summer morning and loved it. No glass left, and not much in way of "decorations" --but check out the description, picture, and map at this website.
http://www.gardenvisit.com/garden/st..._church_garden

Texasbookworm, what a lovely setting for St. Dunstan's - shades of Coventry, still standing...

If you want ornate decoration, it's hard to beat Brompton Oratory on Brompton Road near V&A Museum. Baroque interior.

All Hallows by the Tower

Do you know the nursery rhyme "Oranges and Lemons". You could visit all the churches mentioned http://spitalfieldslife.com/2013/03/...mons-churches/

There are links to other London churches on the site

I appreciate all these suggestions and links. Alec, the Brompton Oratory is nice indeed! I try to go there for mass when I'm in town and always go visit even if it's not mass time.

For something slightly different, how about Holy Trinity on Sloane Square, an Arts and Crafts Church?