Hi FCT
In my defense, my portfolio allocation to UK stocks is modest. Before the s*** hit the fan it was running at 27% of my equity allocation (it's now 12%, which mostly reflects the fact that my UK equities had stops on them so were sold very quickly). That's more than is justified by global market cap weight, but not as much home bias as most people run. In my partial defense, the UK has had a strong value signal for as long as I can remember, which would justify a higher weight even without home bias. I could also trot out the well rehearsed argument that UK stocks, especially large cap, have a large exposure to overseas earnings since many are multinationals that just happen to be listed here.
The other important point is that I buy individual UK stocks, and internationally I've always used ETFs (I don't use stops in my ETF portfolio; this is manually rebalanced). Historically, I choose to buy individual UK stocks and ETFs elsewhere, just because it was easier. When I started investing it was very difficult to buy US stocks through a UK broker, and expensive.
Because I can buy individual stocks, it means I can implement a value based strategy. This should attract a slightly higher Sharpe Ratio than just collecting Beta, so it also justifies a slightly higher allocation. All in all I'm happy with a UK equity allocation of between 20% and 30%, and I'd probably end up back there when the smoke clears.
GAT