To answer this in a slightly different way, Great Britain's diplomatic isolation had a negative effect on their strength for most of the 19th century. But It wasn't until Germany reunified in 1871 that Britain became aware of that fact. From about 1815 on, European countries were weak, poorly lead, or divided, and there was no state that could hope to threaten English hegemony(supported with the Royal Navy). Britain isolated itself diplomatically because it didn't have the need to forge strong bonds and alliances until Germany industrialized and began to catch up in power. Had they formed those diplomatic ties earlier in the 1800s, Britain's power would have been arguably much higher