I didn’t realise until a few days ago that the UK Government Petitions website is searchable. It’s not quite down to “Don’t tell him your name, Pike” level – but you can find out how many people from each parliamentary constituency voted for a given petition. So you can see in what areas support is strongest – and where they really don’t care.
Obviously I searched for the most popular antisemitic petition I could find, as you do. Fortunately there is nothing of that nature currently live: but in 2015 there was a fine example of antisemitism masquerading as anti-Zionism: “Benjamin Netanyahu to be arrested for war crimes when he arrives in London” This attracted 114,122 signatures before it closed in February 2016.
As a control I compared it to the most popular petition which was likely to attract the sort of leftish, anti-establishment progressives who might have signed the first petition – but without the anti-Israel element. This is still open: “Prevent Donald Trump from making a State Visit to the United Kingdom”. As of 29 April 2017 it has garnered 1,863,606 signatures.
There are 650 constituencies in the UK, so on average 175 people from each should have signed the Netanyahu petition. More than 840 signed from: Bethnal Green (1665), Poplar (1528), Bradford West (1347), Birmingham Hall Green (1323), Blackburn (1319), East Ham (1311), Ilford South (1292), Birmingham Hodge Hill (1101), West Ham (1069), Leicester South (876), Rochdale (866), Bradford East (858) & Birmingham Ladywood (847).

On average 2,867 people from each constituency should have signed the Trump petition. More than 10,000 signed from: Bristol West (13177), Hackney North (12346), Hornsey (11848), Bethnal Green (11499), Holborn (11309), Hackney South (11166) Brighton Pavilion (11136), Islington North (10776).

What can we learn from these figures? Most importantly, that the Israeli/Arab conflict is a long way down on the agenda of even the most left-leaning politically-minded Brits. Secondly, that there is no drive to intersectionality: no underlying linkage between opposition to Trump and opposition to Israel. The only proportional demographic overlap with these petitions is in the East End of London, specifically Bethnal Green. This might be expected, as it is home to both the hard left and a massive Muslim population. But anti-Trump centres outside London (Bristol, Brighton) seem to have little or no animus towards Netanyahu or Israel. So where is the anti-Zionist animus concentrated? Bradford, Birmingham, Blackburn, Leicester and Rochdale – all very large Muslim centres.

Conclusion: anti-Zionism is just not that popular a cause in Britain, even among the hard, anti-colonialist, anti-American, anti-capitalist Left. But it does obsess a worrying large percentage of British Muslims. Below is the spreadsheet giving all above-average constituency figures: judge for yourself.

Anti-Zionist to Anti-Trump Petition Map of UK