I recommend the eyebrow threading service at Essential Therapy. The ambience is lovely and relaxing, and even though you're not getting a relaxing full-on treatment like a facial or a massage, you get to lie on a comfy bed and are treated like a valued customer (this is in contrast to the similarly-priced 'sit in a shop window on an uncomfortable chair' threading experiences available on the high street). Both times I've been the therapist has asked me what I'd like in terms of shape/grooming, and has made sure I'm happy with the result before I go. Your eyebrow area is carefully cleaned before threading, and a soothing tea tree treatment is applied afterwards. It feels as pamper-y as threading can!
The only thing that could be improved is the smoothness of the payment side of things - the last time I went it wasn't clear on their system whether I'd pre-paid in full through Treatwell (I had) and I had to wait while they took some time to check. Just a small thing! Also one person on the phone kept on referring to the threading therapist as 'the girl' which was a tad unprofessional and made the therapist seem less qualified than she is (I checked and she is a senior therapist).