The official description for this sandwich is:
Roast chicken breast, curly lettuce, free range black pepper mayonnaise and tomato on malted wheatgrain breadAlthough this sandwich was perfectly serviceable, I felt a little let down by its lack of flavour. The 'black pepper mayonnaise' was intriguing, and a large part of what drew me to this sandwich in the first place – in the end, though, the black pepper never really made itself known, and I would've been hard pressed to tell the difference between this and ordinary mayonnaise.
Unfortunately, this rather set the tone for the rest of the sandwich experience – whilst perfectly edible, this sandwich and all its ingredients fell a good way short of 'spectacular', landing instead in 'disappointingly tame'. I would not buy this sandwich again.