Laundromat London near Green Park

In case you don't get a reply here and search for it yourself, the local term is "launderettes."

A bit of a look round Google, and there are a couple of Launderette/Laundromat, but not really in an easy place from Green Park area, the vast majority are dry cleaners. I've never used them myself, but you could try 'Launderapp'. A typical 6Kg bundle of washing is £12 collected and delivered, which is not far past what it will cost you to go and do the washing/drying yourself, and you'll be able to have it collected from and delivered back to reception, so won't be wasting any of your own time.

https://laundrapp.com/

You can use the Sheraton post code to enter the site and look at the prices... W1J 7BX.

There is a 25% discount code for new customers on the site also... use code Welcome25.

JUst be aware that the turn around time for Laundrapp is 48 hours. I thought about using them until I saw that.

You might also consider asking at the front desk. They may have a list for guests who ask.