I would leave the swift as P. mathias.
The 2 species can be quite difficult to separate.
This is a pristine individual & the forewing shows a dark shading.

The Sunbeams are rather confusing in Singapore.
If we were to follow the key the 1st is C. tagalica & the 2nd C. saronis.
However the undersides appeared to be identical.

C. saronis female.
Note the end of the forewing band is more rounded & the hindwing band narrower.
The image of the male with the red legs is no longer available.
Note the antennal tips seem to be a brighter orange.
http://www.butterflycircle.com/check...Sunny-Chir.jpg
http://4.bp.blogspot.com/-0SkEnFnlt-...eam+Female.jpg

Tentative C. tagalica.
Male
http://img.photobucket.com/albums/v2...raSunbeam1.jpg
Female. Note end of forewing band slightly slanted & irregular; hindwing band broader.
Note in both sexes, the antennal tips are duller orange.
http://www.natureloveyou.sg/Minibeas...350%20(10).jpg
http://wanderingbutterflyeffect.file...eea554860c.jpg

TL Seow