There are remedies, such as an insectidal wash for the area, or a damned good soaking to put them off and send them elsewhere. They'll be off soon, all the winged females emerging to start new homes somewhere, and the activity will subside. Just keep the lawn well watered and fed to prevent the ant's workings from affecting it too much. Ants are useful to us, (clearing up rubbish, seed dispersal etc.) so I'd brush off any mounds of fine soil and ignore them.
Phil J

Always remembered my grandad used to pour boiling or v. hot water in the nest.I suppose there will be a remedy as Phil says that would be more permenant

Grandmagolf,

You're the third person in 48 hrs to ask this exact same question - it's the time of year I guess.

Generally speaking, as Phil says, ants are useful in a garden, and form an extremely important part of the ecosystem as a whole, so I'm not an advocate of killing them off unless absolutely necessary. That said, ants they can become problematic in pots or disruptive if they build nests in the wrong place such as your lawn for instance.

Ecocharlie sell something called "No Ants":
http://www.ecocharlie.co.uk/grow-your-own/pest-and-disease-control/nemasys-no-ants.html

This is an environmentally friendly nematode solution that you simply water into the soil and which will effectively drive the ants out of the lawn and the immediate area surrounding it.