If we are going with a date of 1803, it cannot be Gainsborough, since he'd have been very dead for five years by then! Having said that, whoever actually painted the portrait for P&P2 had a good understanding of Gainsborough's brushwork- there's an airiness about the face which is very Gainsborough-esque.He/she might have been trying to do an impression of a Gainsborough acolyte painting Mr Firth-Darcy's portrait.

Neither, I guess, would it have been Lawrence. Lawrence specialised in glamour portraits of young women, and although he was a good artist, and did several well-known portrait of men, there's a certain vacancy about the eyes of the Lawrence portraitees which isn't obvious in the Firth-Darcy portrait.

Do we still want to assume it's an English artist that (a) JA would be referring to, and (b) that was being copied in the P&P production?