Of course the simple and accurate answer is no-one knows. Whatever you do is a risk/gamble.
All I can say is that it has been widely reported recently that prices in Dublin have stalled and in some areas are falling.
Whereas I believe prices in London are increasing. Also, you should check this, but I would presume yields in London would be higher than Dublin since Dublin yields are a joke...which would indicate to me that there is greater scope for increases in London. But like anyone who answers, I don't actually know the correct answer...