In general, the British value time-keeping for business arrangements. If you set up a meeting for two o’clock, the chances are your counterparts will arrive on time or just before. Since the British are so time conscious, sometimes you may feel their lives are very rushed. In fact, however, they are only doing their best to avoid losing time, which is valued as an economic resource. It is considered very impolite to arrive late for a business meeting. If your delay is inevitable and you arrive late, it is usually sufficient to excuse yourself with an apology. If, however, you are running more than a few minutes late, you should call ahead to apologise and give an indication of how long you will be; in the case of a longer delay that would compromise the value of attending the meeting, you should consider offering to postpone the meeting to a new time and/or day. The busier people are, the greater the likelihood that they will have to leave for another engagement, so respecting their time is very important.
Attending social events is slightly different, and guests may be expected to arrive about fifteen minutes after the specified time, but this is contingent on the nature of the event and the number of attendees. You need to be particularly careful when using public transport, as some journeys may take significantly longer than advertised. Public transport, such as trains and buses, is generally reliable although it is recommended to allow extra time, especially if travelling in winter when the transport network is usually unable to cope with even the slightest flurry of snow (unless you are travelling in Scotland). The golden rule is that the more important the appointment, the more time you should allow for potential delays.