In the 18th century, was it only the American colonists who had "virtual representation" in Parliament, or did British citizens in England have...

The concept of "virtual representation" did not just apply to the American colonists, but to the people of Great Britain as well. Edmund Burke, in a famous speech to the Electors of Bristol, responsible for returning him to office, explained it like this:

Parliament is a deliberative assembly of one nation, with one interest, that of the whole; where, not local purposes, not local prejudices, ought to guide, but the general good, resulting from the...

The concept of "virtual representation" did not just apply to the American colonists, but to the people of Great Britain as well. Edmund Burke, in a famous speech to the Electors of Bristol, responsible for returning him to office, explained it like this:

Parliament is a deliberative assembly of one nation, with one interest, that of the whole; where, not local purposes, not local prejudices, ought to guide, but the general good, resulting from the general reason of the whole. You choose a member indeed; but when you have chosen him, he is not member of Bristol, but he is a member of parliament. 

In other words, Burke did not feel obligated to advance the interests of the Bristol merchants who elected him, but the people of Great Britain as a whole. This concept was fundamental to the British constitution, and it was rooted in the reality that many Parliamentary election districts, or "boroughs" were actually based in rural areas with very small populations. These boroughs could still choose members of the House of Commons, while other rapidly growing urban areas, like Manchester, could not. It might be argued that the concept of "virtual representation" was invented to justify this situation, as well as in answer to the complaints of the American colonists, but the point is that the English people were, in theory, no more directly represented than British subjects in America. They also, not incidentally, paid much higher taxes than people in the colonies. In reality, many Parliamentarians were in fact the direct representatives of the people that elected them, and Burke's ideal of virtual representation was in many ways nonexistent in real life, however. But the British could argue with propriety that they were not obligated by the English constitution to grant representatives in Parliament to the Americans.