Unfortunately- we are judged on how we look and if we are to have influence with clients/ committees we do have to look at least well groomed and up-to-date. I'm female, so I have probably experienced more judgement in this area than men do. (given you mentioned the Delia's catalog I assume you're female too). Yes, I say ditch the Delia's.
Here's what I've done- I hope it helps you:
1. Buy a few button up casual oxford-ish shirts in classic colors (I have white, blue and light red)
2. Buy a few pairs of flat front, well fitting pants (I have khaki, navy and chocolate brown)
3. One blazer ( I have navy)
The classics last so much longer no matter the style and you still feel put together. Most of these can also be found at Goodwill or other Thrift. I actually score my three pair of professional pants at Goodwill and they were Brooks Brothers!
I like this! And I suppose I need to be more positive about what I have since it sounds like my work wardrobe is bigger than yours and I only go into the office for a few days every other month or so.
My current work wardrobe is:
3 pairs of work slacks - 1 black wide leg (2002-ish from Banana), 1 black cigarette pants (2010-ish), 1 pair olive green skinny pants (2 years old)
2 sweaters - 1 black turtle neck (old- also from banana), 1 v neck maroon tunic (2 years old)
5 button up/blouses (chambray, white, navy blue, navy and red pattern and a black and white stripe (the last two are from Delias and probably 20 years old)
2 summer dresses (black and black and white stripe - new this summer)
1 black cardigan (2000)
2 blazers - 1 red (2011) and 1 black (mid-aughts and looking aged)
I really thought that was enough for my occasional work trips but the last two times I went in to the office different women commented on how I always wear the same things. It made me very self conscious and in the past few weeks I've turned a very critical eye towards my closet.
My work "wardrobe" is my most extensive. Casual clothes include 3 pairs of jeans, 6 t-shirts, and a few flannel button downs and a hoodie for the winter (as well as the work sweaters).
Related to GuitarStv's comment "Style is determined by how good looking you are, and your confidence while wearing something " - I would definitely believe that I'm not projecting confidence in what I wear but my face wouldn't curdle milk or anything so maybe i just need to make sure people are looking at my face :)