The Singer Apollo was the first Singer safety bicycle, introduced in 1887. It was built until 1891-1892.
As you can see in the pictures it was an individualistic design, with some nice details.
The 1891 Singer catalogue shows two models of the Singer Apollo safety. The model you see in the pictures was the simpler version, with socket head. It can be identified easily by the spring under the head tube.
Then, there was the 'special Apollo' which had a ball head, the Singer patent steering lock and it was lined. As a consequence: the normal Apollo was not lined?
I made a page with some details of the later model Apollo, showing the steering lock and single footrests. Click here to see it.
The bicycle in the pictures was sold in 2014 at Bonhams auction in London. Serial number is XX796. Without the complete serial number, it's hard to say when it was built. Last three digits of the serial number are engraved on top of the front fork.
Don't look at the lamp, it's from the 1920's. The auctioneer was friendly enough to send me some detailed pictures. We see a very original bicycle, and really, I think I should have gone to London to buy it.