My lawn seems to be going downhill year by year. Every year I regularly mow, scarify, feed and I feel look after it well, but it seems to be getting worse year by year.

The lawn is UK based, not covered and reasonably large, some of the gaps are from where I scarified but nothing grew back. I laid seed but nothing came.

Attached are photos of it but Im not sure if I should scarify, compost, or just continue to be defeated? Also, when I do something, when should I do it? Help!