The borough's favourite birds look set to nest in the town centre again.
Sutton's pair of peregrine falcons, named Perry and Gwynn, have roosted on the top of Quadrant House for several years but there were concerns after they failed to breed last year.
However experts say it looks like they will be laying eggs soon after Gwynn started 'pancaking' - where she hunkers down close to the ground as if she is about to lay - and clearing small spaces in the roof of the building where she could deposit eggs.
Although she is not expected to actually lay the eggs for several weeks, observers around Quadrant House have noticed an increase in peregrine activity in the area.
Rob Dolton, leader of a group of volunteers who keep an eye on the birds and even have cameras on top of the building, said: "It's at this time of year, January and February, when they get together a little more and mate.
"[Gwynn] has been pancaking where she snuggles down and it looks as if she's about to lay but that won't actually happen for a little while.
"Fingers crossed we will get a nice clutch of eggs this year.
"They didn't nest last year, or they may have done somewhere else and it wasn't successful, so we're hoping this year will be different - it looks promising at the moment."
Peregrine falcons are rare and breeding pairs are even more rare.
Two years ago Perry and Gwynn had a clutch of five eggs, something only one or two breeding pairs manage each year.
The birds are watched over by a team of volunteers which has have everyone from retirees to a judge in its ranks.
They keep an eye on the top of Quadrant House - the town's tallest building and home of the Sutton Guardian - using cameras they have installed and eagle-eyed people in the area nearby.
Mr Dolton added: "It's really thanks to the team at Quadrant House that we're able to do this and that these birds have able to thrive."
The peregrine falcon is the fastest animal in the world, able to reach speeds of up to 200mph when it dives.
- 'Irreplaceable' sculptures stolen from museum exhibition commemorating Battle of the Somme
- 7 unusual family days out in south London and Kent this summer
- 'Can I have a Big Mac?' – London Fire Brigade reveals top 10 weirdest 999 calls
- Southern Rail cancel trains because of 'graffiti'
- Judge's secret ruling on Ellie Butler murder should be made public, appeals court rules