I had the pleasure to play Battle of Britain with 3 friends and we had an amazing time.
We were mostly seasoned escape room players, with a total of probably 50+ escape room between the four of us, and we found the puzzles very smart and engaging, not too hard, not too easy, and there was plenty to do for the 4 of us.
The room worked really well thematically as well. I could tell it was high quality stuff - in some escape rooms I've done, props were all worn down because they'd been used so much, and some objects sometimes felt fiddly or poor quality. We didn't have that issue with Battle of Britain at all!
Besides, our host, Sara, was very friendly and very attentive to our every move in the room. She observed us well enough to assess whether or not we needed clues - and in the end, we didn't need any, but it's great that she didn't give away anything, as I've had that issue with other escape rooms in the past where hosts aren't really paying attention to what you're doing and over-clue you as a result.
I'd thoroughly recommend this escape room for seasoned players looking for a challenge, and we found that the room worked well for 4 people. Less than that and we might have struggled to reach the maximum score.
I think I can safely say this is one of the best escape rooms I've ever done, and I've done many!