New Town Flowers

Dotted around the New Town in Edinburgh there a series of private parks for the use of local residents who also pay for their upkeep. They are well fenced so it is seldom that you have a chance to view them from the inside. At the end of Great King Street and tucked in by Royal Circus there is one of these parks and it usually alongside this garden that I park when attending Edinburgh Photography Society as I did last night. I was surprised to see so early in the season clusters of blue flowers. For a moment I did a double take and thought they were very early bluebells but when I look more closely I realised they weren't. Despite searches for wild flowers on the internet  and elsewhere I have not been able to identify them so I would be pleased if someone can tell me what they are. Identification features are :- six petalled, long thin leaves springing from the bottom of the plant abut 10-15 cm high, growing in shady deciduous woodland. Maybe I've got the wrong end of the stick and they are actually cultivated rather than wild flowers ?