EUR and GBP are highly correlated currencies, and the pair therefore has a very low historical volatility score. This is the least volatile GBP pair - GBP/JPY being the highest (it's the most volatile of all the major pairs) and even GBP/USD is higher.
Low volatility suggests lack of follow-through on TA signals, transient and inconsistent trends, longer holding times for the same % profit.
If you can't get hold of historical volatility or you want something more responsive and relevant, take the ATR of this pair and convert it to a pecentage of price - do likewise with the ATR of GBP/USD - EUR/GBP will almost always be lower.