Nice image of this little guy. You certainly got your money's worth on that bird seed!
Assuming that, as always, the colour is a very faithful rendition - I would be tempted to suggest this is a Willow Tit, rather than a Marsh Tit. The differences are slight, but I think the grey of the wings and back and the pale patch on the secondaries carry it through to Willow. ( I had to look it up!)
Gerald, Andreas I woud probably go for Marsh tit.
Visual ID is not easy and is unreliable, the certain way to tell the difference is in the bird's call. The Willow tit has lighter toned tune in a repetitive call, the MArsh is lower pitched and a little coarser in tone.
Regarding visual ID the bird appears to have a pale spot on the mandible, this tends to indicate Marsh tit, the colouring in the wing plumage is varaibale with age and with species. Having said that Gerald you just may be correct!
Returning to the image it looks dandy to me, colours look ideal and details are there throughout the tonal ranges. Composition looks fine, the fact it is on a big perch as opposed to a smaller one doesn't trouble me because the subject is a good size in the frame and draws it's own attention. The apparent bird seed could have been easily removed if you felt inclined. You can be proud of this it's not too often we see such clear images of these little birds.
The bird is uncommon in UK and there are a few reserves in the country making dedicated efforts to produce better nesting environs.