Offices in the UK are based on different grades predominately split between grade A, B and C. There are many factors that determine the grade of an office. The obvious factors are quality of the office and building and this applies equally well to serviced offices in London.
Grade A offices are those that are newly refurbished to a high standard which will include air conditioning, usually raised floors and other amenities such as passenger lifts. This sort of office can be found in places such as many Serviced offices in Mayfair but are not limited to London or particular areas of London.
Grade B is offices that maybe lacking slightly in quality or could be so because they are in second hand condition as they were previously occupied by a previous tenant. Some period style buildings limit the quality of an office because they prevent certain amenities. For example in Mayfair some of the period buildings you find typically on streets such as Upper Brook Street consist of smaller buildings which are restricted preventing the benefit of a passenger lift or a new VRV air conditioning system.
Grade C usually is lower quality that is more suitable given its affordability. Offices under this grade would be lacking in a number of amenities however they still provide useable basic space for businesses.
It is advisable businesses consult a professional in order to way up their options and to advise them on what type of office they should consider in line with their budget.