Royal Court Hotel
My update to the enquiry ...
On arriving off the train from Nairobi I asked for the Royal Castle Hotel and was instead deposited at the Royal Court Hotel. Which I can wholly recommend. About 7 minutes from the train station and 10 to the port if you've a shipment coming in, it is very clean and modern, has both private security and the police stationed outside for secure parking and a rooftop bar/pool and resto - all for 5000 KES (I've a twin room for one occupant).
Internet is extra at 1000 KES per 24H but a very good breakfast buffet is included. Not the cheapest overall, but a really decent place to stay if you need to work with your shipping agents and/or the port authority/customs as all are within minutes of here - a really good base of operations in Mombasa.