Looking at your headers, I take it you're in the UK.  And I
can't comment on brand availability there.

It can be very important not to mix coolant chemistries.  Some
react very badly together and can completely block your coolant
passages.

Colour is often (but not always) a reasonable indicator of
coolant type.  Unless you know what's in there, it would be
wise to do a very thorough flush with water when changing it.

The absolutely safe option for the brand and type of refill
would be to buy Mitsubishi coolant.  It's unlikely to be overly
expensive for what it is, and its additive package will be
compatible with the alloys in your engine.  If it's sold as
concentrate, mix it with distilled or demineralised water only.

John