The characters who generally receive the most character development are the young male characters; these nearly always fill a lead role and as such are the 'face' of the programme. This is often highlighted in the programme's marketing; and as such people now often expect to see male cast members outnumbering female cast members. This is likely to draw in a male audience on the basis that they often associate female-led programmes as being targeted towards women.
Female characters are likely to receive little character development and are often placed in the cast as "the chick", rather than as a character who will be a main part of the plot. Unless of course they are the lead character's love interest. Y'know, because it's not like that's been done thousands of times before.
Ethnic minority characters are often shown as having completely different personalities to the white British characters in the programme - which goes with Alvarado's (1987) theory which says that ethnic minority characters will be exotic, dangerous, pitied or humorous.
When ethnic minority characters are shown in a British TV programme, it is often highlighted to the viewers over and over again that that character is of an ethnic minority, even if it is not directly stated in the dialogue. This can be through the writers playing on stereotypes, referring to their backstory etc.
It is also not uncommon for programmes to make use of token characters for the sake of making the programme appear more diverse. This isn't as noticeable when COTD's appear as ethnic minority characters or when an ethnic minority character is in the main cast from the beginning, however it does seem suspicious when a minority character is added to the cast several series' in as a desperate attempt to widen the appeal to boost ratings...
Disabled characters are generally presented differently in the sense that if a disabled character is shown, he or she will either be a token character for the sake of equality, or will have a completely formulaic "supercrip" storyline involving 'this person is disabled. Poor them, let's find a compromise to give the illusion of them getting over this limitation'. You would have thought someone out there would have found an original storyline to use which involves a disabled character, but no, TV writers are still a bit too lazy for that.
In modern TV disabled characters are always shown as being vulnerable and in need of care, and often involve another (able) character having to look after them. Historically disabled people/characters with some kind of handicap were often shown as bad guys (think Captain Hook, Dr. No, pretty much every pirate ever), due to the traditional ideology of "if we don't understand it, let's all be scared of it for no apparent reason".
Karen Ross (1997) - says that disabled people are generally not in favour of traditional representations of the disabled and are keen on sorting out "respect issues" in the media. They want to see more authentic portrayals of the disabled, and would like to see disability presented as more of a normal, every day thing as opposed to having to be a major story feature.
So yeah, I'll probably add on to this another day as there is tons more to talk about.