I was staying nearby in SW1 overnight in London and googled Dukes spa as I needed my nails looking smart for a big evening event. From the hotel reception, I was ushered into the spa and then taken to a treatment room as there was no "nail unit". How nice to have a private treatment than the usual crowded nail bar experience. I had a quick manicure and gel/ shellac paint done by a most charming beautician called Annie from Greece so had nice chat about Greek holidays. It was excellent value for money at £25 in a well appointed venue. You could pay this in some busy nail bar. I had no spa treatments so cannot comment on those services.
The masseuse was incredibly friendly and gave a brilliant massage. The atmosphere could have been improved by relaxing music and dimmed lights or candles. All in all I thoroughly enjoyed it.