Thomas Agnew & Sons.
The latest Thomas Agnew & Sons label that I have come across is almost identical to the first one posted, however the text 'Frame Re-Gilt By' is omitted and a new line of text states: 'Fine Art Publishers To His Majesty' also there is a reference number 1618
Here below is another Thomas Agnew label, this must be earlier than the one previously posted, no sons in the business yet, the address only mentions Manchester and while the street is the same, it is a different number. Posted on 1st August 2014:
Label below posted on 23rd July 2014: