Unexpected high SG

I just brewed the following.

30 litres length from 9 lb pale malt and 20 oz grains mashed at 68 deg C. SG 1.074

Too high?

What kind of grain? What are you making? 'Too high' is relative.

Are your volumes accurate?

I just checked the volume with an identical bin, it is 25 litres, not 30, sorry. The grain was maris otter crushed pale malt, 1 lb crushed crystal malt, 4 oz crushed chocolate malt. Mashed in 15 litres of water (measured in). Fly sparged. It is an ordinary english bitter, but I prefer plenty of colour. Hops were goldings and fuggles. Boil time was 90 minutes, but I added water throughout the boil to keep the volume constant. I just invested in a new boiler so its a bit experimental. Previously I could only boil a maximum of 15 Litres. Thanks.

Yeah, you're too high for an ordinary bitter according to the style guidelines:

BJCP 2008 Style Guidelines - Category 08

Yes, thanks for that, but would I get 1.060 from those ingredients (=1.072 for 30 litres as posted) ?