Hammerite smooth black paint available from halfords in airosol cans is perfect for the job and if you follow the insructions carefully it will look like new
Remember that the paint will need a few weeks to fully harden so handle carefully until really hard.
On Aluminium, a primer is recommended. If you choose not to use the primer then it will probably be better not to go for a polished finish prior to applying the paint
Remove old finish with cellulose thinners and/or wire wool
You will notice that there is a primer underneath the original paint
Hope this helps
John