During daylight hours
							                                
                                        
                                    
							                        
                    
                            When it's busy
							                                
                                        
                                    
							                        
                    
                            In the rush hour
							                                
                                        
                                    
							                        
                    
                            At any time
							                                
                                        
                                    
							                        
                    References
Page 55 in Know your Traffic Signs states:

The red cross means no stopping, not even to pick up or set down passengers. The sign is used to indicate a 24-hour clearway (usually on a rural road) or may be incorporated into other signs with the words “No stopping” (e.g. the “no stopping except local buses” sign at bus stops). On a 24-hour clearway,the prohibition of stopping applies only to the main carriageway.You may stop in a lay-by unless there are signs to say otherwise.A 24-hour clearway does not have any special road markings, but there should be smaller repeater signs at approximately one mile intervals.
 
	 
	