1. Here it is.

2. Here comes X.

Although the /r/ is pronounced in #1, in BrE, it's very light: not at all as strong as the /r/ in "rats", for instance, or the AmE pronunciation of "here".

Additionally, this would probably only apply to standard southern English: in some forms of Estuary English, for instance, you would hear a glottal stop in #1, rather than an /r/. In Scottish English (and some rural dialects), you would probably hear the /r/ in both #1 and #2.

MrP

I'm sorry that I don't know how to use the IPA or other pronunciation symbols, but there are also accents within the US where the R is not strong - the Boston accent is frequently made fun of with the phrase "pahk the cah in the Hahvahd yahd" where the r's disappear almost entirely. In fact, after living in New England for so long, I answer to "Bob" because that's what "Barb" sounds like. (The non-prevocalic R goes away.)  In Maine, words that end in -er are pronounced like they end in -uh -- like if you speak softly, you are speaking in a "whispuh." (There is a net conservation of R's however, because they throw them on the end of words that end in a vowel, like "pizza" becoming "peetzer" and "Augusta" becoming "Auguster." So there is balance in the universe.)  In Downeast Maine, "here" is close to "hee-yuh."

Most British speakers combine words in phrases like "there is" into a single continuous sound and the r is sounded for convenience.  This is less common in German, where words starting with vowels are still seperated from the previous word, although ironically, in  German, the written words are more likely to be combined into one!

Having said that, some British accents (Scottish, Lancashire, Cornish etc) pronounce "r"s at the end of words - like in American English - but these are regional differences that I wouldn't worry about when learning English!