Sorry for the long delay in giving my promised update! As you might have gathered from my last post, I opted for Oxo Tower for our main dinner. No regrets, it was most enjoyable, the view was terrific and it felt like a special occasion. The restaurant staff were also extremely friendly and helpful, contrary to some of the comments in reviews, so that was a special bonus. The final bill was hefty, but well worth while for a memorable occasion.
We managed lunch at Busaba, another of the recommendations above. Also very nice, but one of the vegetarian dishes was disappointing - I forget which.