I had a new lawn laid at the weekend, and it already has brown patches and lines, but not where the joins are!
-Rowlawn medallion turf
-Ground was fully rotovated
-Nothing else underground
-No treatments added
-No pets, and no animals accessing garden
-South East England
-Sprinkler on for around 20-30 minutes everynight
-Sunny each day
Any thoughts about what is causing this, and how to deal with it?! Is this common with new lawns?
That is strange it is like somebody rolled a heavy cart over it. If this is new turf. Water it 4 times a day until it is rooted. Feed it once a month for the first year and don't be in a hurry to mow. Mow it high for summer. The grass should be able to fill it in if not then you can do some repair work. But for now I would just try to keep it from spreading.