Its to allow plants like clover in the grass to flower to provide nectar and pollen for bees/butterflies/moths etc.

Several conservation groups are advocating mowing less frequently; mowing sections and leaving other areas un mown; not mowing at all until later in the summer/early autumn.

It wont be acceptable to all but any extra wildflower sections will help. My OH is resisting all of them but has conceded to lift the blades. We are growing wild flowers in amongst regular garden plants in the borders instead.

As SBG says, allows flowers to bloom & bees etc to feed

I'm following but admit some is down to health & idleness, now I can be "on trend" and virtue signal :-)

But I've never been one with a lawn, I have a small patch of grass with daises & dandelions, which I would dig up & plant veggies in if it wasn't also the drying area for my laundry

Thanks SBG I find it is too cold for the grass to grow anyway. I have a wooded part that I let any thing grow in and so far blue bells, cowslip and primulas looking very pretty also lots of things coming up which have somehow self seeded and am over run with lesser celandine.
Thanks Grandad my lawns have become mostly wide paths as I have taken so much for bigger beds over the years,

We have just mown our front lawn, sorry! Its been left for weeks as it was thick with self sown celandines and primroses. Now the other side is half self heal & a little silverweed & lots of dog violets on both.Happens every year but mowing late doesn't seem to have any adverse effects. They would go berserk if left any longer... We do "the dandelion job" (picking the flowers before they seed)on all three lawns every day weather permitting to try to prevent even more seeding but with a field nearby its a losing battle. The creeping buttercup on the back lawn does get weedkillered though occasionally as long as my energy lasts which isn't long these days....

DRC I envy you your cowslips!

I think that perhaps a new laid grass lawn could be interesting to see what comes up, but we tried this on the field at the back and just had rank grass! The front 'lawns' are mostly creeping potentilla, Self-heal and rampant violets and I have been forbidden to even plant the snowdrops in the grass - let alone not cut it!

Honey our influx of clover came from a bit of turfing that the workmen laid when they resurfaced the drive. You never know what you'll get from bought turf...

The trouble with fields as far as flowers go is most of them seem to have been treated to eradicate them. There is a field by a small river not far from us that used to be covered with cuckoo flowers in May until it was drenched in weedkiller, presumably to remove all the dandelions. It was only ever used as an occasional pasture anyway. Happily it did recover after a few years but it was so sad to see it plain in the meantime.