Why/How from Portsmouth (1800) to Malta (1821)? + "Ticket" letter & number?

[Christine in Herts]

My TNA visit on Friday turned up another snippet on OH's ancestor, James WHITEHEAD, with his traces of records on HMS Redpole in January 1822.

Firstly the why/how question:
Born in St Crux, York (rendered as St Cruse or St Cruise, in the Redpole books) on/after 26 Feb 1800.
Baptised 5 Apr 1800, St Thomas, Portsmouth

Volunteered for the Redpole, 1 Jan 1822, Malta. Unless there's a ship called "Malta", I was wondering how/why he'd have made that journey.

Then "Ticket" letter & number?
One column of info refers to "No. & Letter of Tickets". Most rows are empty for that column, but James's has "ML 887". Does anyone know the significance of this, and whether/where I could follow this up?

Christine

[Christine in Herts]

Just found this which appears to illuminate the second part of my queries:

http://www.barnettmaritime.co.uk/navalpaymuster.htm

... and, maybe, even some of the first:

Contrary to popular belief, men pressed were most commonly taken on inbound merchantmen and it is known that in this situation some ‘volunteered’ under duress: thereby gaining a recruitment bounty as some recompense.

Christine