^This is an age old debate. Navy blazer (jacket) + grey trousers + tan shoes and belt is a classic combination. So long as - the jacket has a bit of texture in it so it doesn't look like an orphaned suit coat and the pants are a lighter grey so you have enough contrast.
In the pics you have posted the jacket looks fine (contrast buttons avoid the suit look), but the trousers should be lighter. I would also go a knit tie in a black or French navy, but there are other options.
See picture from the Manton catalogue below: