In the '50s, the RAF seemed to "have a thing" about quick starting and had cartridge starters on types such as the Venom and Canberra, so the Chipmunk must have been fitted with one, for "standardisation" ??... And the "ring pull" was fitted before pull-top cans came in, so who copied who(m)?
For me, the Chipmunk's oddest feature was the flap lever, operated with the right hand, needing a "change hands" on late finals, while when going to "flaps up" , it was only too easy to do one's thumb-nail a nasty mischief on the VHF box as the lever moved smartly forwards, pulled by that strong bungee. ("An 'Ouch' to Remember" to this day).
About the Canadian "bubble" hood - it was brought in after most of the RAF's Chipmunks had already been built, and was no doubt felt by the "Pahs that be" to be an unnecessary piece of "go-faster" kit ...