When Sil first posted this, I looked for a print in the online poster shops, but no luck. Even a wider search on Google came up with nothing.
So in true Blue Peter* style, you could try a DIY poster, not a large one, A4 (approx 210 x 300mm) or even A3 (approx 300 x 420mm).
Right click on the Sil's picture, and click on "Save Image as". When you've saved it, open it with your photo-editing software. Use the re-sizing option (in Paint Shop Pro use Shift-S) and increase the pixels by say, 4 times. When increasing the pixels, use the "Bicubic" re-sampling option if available, or if not then use the automatic option. Save it again by the "save as" command as another file.
Now you can print it at home, or take it to a print shop.
If you want to experiment regarding size before spending money at the print shop, crop the picture to use a small part of the picture, eg face & hands, and blow it up and print at home to see the quality of the image.
Remember to use the "Save as" command and save to another name, and not the "Save" command when saving to preserve the original.
As long as you don't look very closely, and certainly when it is behind glass on a wall, you should have a serviceable, if not huge, poster.
Just one thing, I can't vouch for any copyright issues. As not many of us have printers available bigger than A4 at home, hence we have to go to a print shop for larger ones, it maybe something to bear in mind.
Happy experimenting
Mike
* UK children's programme that, when I was young, was famed for showing kids how to make things themselves from washing up liquid bottles, toilet roll centres, sticky-backed plastic etc.