Chemical
In lawns, use a weedkiller such as a 2, 4-D-based herbicide to remove self-heal. Apply in cool, moist, calm conditions when there is least risk of accidentally damaging nearby garden plants.

Thank you, Michaella. Although I resist using chemicals I feel that resistance is futile - so chemicals it must be!

This is an aggressive weed but if you dont want to use chemicals, can be reduced by regular mowing, rake over to make it stand up more and mow every 3-5 days.

I love it!! But then I don't have the traditional velvety lawn. I think it's a 'good' year for Prunella depending on one's perspective, so i guess they like being soaked.
Good luck in your endeavours though Lutley.

I haven't got a "velvety" lawn - far from it, but I do like to see some grass! I have started to take some out by hand which isn't too difficult and its theraputic, if time consuming.
I like it as groundcover in damp, shady parts of the garden as it is very attractive to bees and hoverflies. I just don't want it in the grass!

Sorry Lutley, didn't mean to offend you or anyone who does have a velvety lawn. Like most people my age, I was brought up with that ideal of a perfect lawn and I still admire them when I see them. I know how much thought and work goes into keeping it weed-free.
I wouldn't mind some self heal in my grass at the back but it's very shady and they don't seem to like it. There is some in the grass at the front but we pay a gardener to regularly mow the lawn and this keeps everything down.
You say that it does well in your damp shady places, so as it's so wet this year it might just take hold in the grass or a border. I'll dig some up and hope.

No offense taken - I didn't want to give the impression that I am a grass fanatic who is constantly on bended kness inspecting my sward.
You'll find that the devilish "selfheal" flower spikes will grow to about 10," if not mown. Good luck with establishing it in your shady area.