Grass dying and going brown?

Hi, during the summer I noticed that around the edges on my lawn where the grass seems to grow extra long, there have been lots of brown patches appearing as you can see from the photo. I admit I didn't keep on top of the mowing so I am wondering if the extra long and thick grass had blocked light from reaching the base hence the brown patches? The thing is I have no cut it and the grass is growing back but on top of he brown stuff and the grass blades start quite high up because of the dead stuff underneath.

Is it best to rip up these patches and sow fresh seed or will it be ok? Thanks