Anything new going on in London?

The Chelsea Flower Show is from May 24 to May 28. Don't know how long you will be staying in London.
https://www.rhs.org.uk/shows-events/rhs-chelsea-flower-show

It isn't new, but the London Transport Museum in Covent Garden is very interesting.

The Wallace Collection in Manchester Square is worth a visit.

Take afternoon tea or lunch at RIBA on Portland Place near Oxford Circus. A gorgeous Art Deco building and it usually has a free architectural exhibition to visit. Book online at ribavenues.com.

The SkyGarden on the top of the Walkie Talkie Building (20 Fenchurch Street) is the new go-to viewpoint, and free.

Brick Lane is fun if you haven't been, especially if you're into food.

Have you taken any of the London Walks tours? Those are 1.5- or 2-hour walking tours which give excellent, in-depth information about neighborhoods and sites which might seem self-explanatory on the surface. We took the Street Art Walk in Shoreditch in October which was fascinating. I liked that the guide also talked about some historic buildings, like an 18th-century church, and historical events, such as the Jack the Ripper murders, in addition to street art.

I'm going to be there in May and have done the big touristy things already as well. On my list this time:
Handel and Hendrix House
http://handelhendrix.org/

Botticelli exhibit

http://www.vam.ac.uk/content/exhibitions/exhibition-botticelli-reimagined/about-the-exhibition/
-They also have one opening about the history of undergarments. The clothing exhibits of theirs I have seen in the past have been quite good, so this will probably be as well.

Highgate cemetery

Picnics in the parks

Rolling Stones exhibit
http://www.saatchigallery.com/current/rolling_stones.php

and I agree with the London Walks as well.

I'd look at websites for going ons at Alexandra Palace, check out Graffitti art tours, reserve for the Highgate Cemetary tour. Did u walk along Regents Canal to Canden Lock Market? Found the Jim Henson bench in the Hampstead Heath? Visited Hampton Court? Kew Gardens? Toured the Houses of Parliment? Seen Liberty or Selridges Department Stores? Evensong at St Brides church? Done the Tower Bridge experience ( if u get vertigo don't bother) , walked all of Portobello Market? Seen Richmond Park? Walked the Thames pathway? Visit the sight of the 2014 Olympics? Brick Lane?
Checked to see if tea dances are on at Spittafields Market? Checked out the schedule for Wiltons Music Hall? Taken the train to Durham to see the Cathedral and Castle? Seen the Treasure Room in the British Library. Seen the Hunterian Museum? Visited the Whitechapel Bell foundry? Pollock's Toy Museum? Checked out whats exhibiting at the Royal Academy of Arts? Same for the Photographers Gallery? Timeout is an excellent resource. Look up what you like, art, music, theatre, museums,sport, food, etc. May is a nice month to visit. Enjoy.

Thanks for your very informative email. We have probably done most of these things over the years, the Alexandra Paalce has never been on my list though so I will check it out.