Clumps of grass help please?

Hi folks
Newbie here. Any advice much appreciated!
Last year I planted a turfed lawn. It has come on really well and I'm pleased with it.
Only thing is some sections seem to be doing really well, better than the others. Some small patches of one or two feet wide are really green and grow a lot quicker than the rest of the lawn.
Not a massive problem obviously but I'd love the lawn to look uniform. Any ideas what to do?

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