Robert Craig has a made an interesting post over at the UK Constitutional Law Association Blog wherein he claims that Yvette Cooper’s bill to extend Article 50 would require the Queen’s Consent. If this is true, it would potentially give the Government a ‘stealth veto’ over the bill.
I’ve discussed the Queen’s Consent before, but the TL;DR of it all is that the Queen’s permission is required before Parliament can pass any bill that touches her prerogative or interest. This is distinct from the Royal Assent (which makes a bill into a law), and Consent is only necessary for certain bills (sometimes, the connection to the Queen’s prerogative/interest is extremely subtle–for example, both the Nuclear Safeguards Act 2018 and the Ivory Act 2018 required Consent).
Craig’s analysis of the situation seems reasonable, so it’s likely that the Cooper Bill would require the Queen’s Consent (the Clerks in both Houses will ultimately make that decision). And since Ministers are the ones who ask the Queen to give her Consent, they could block the bill by refusing to approach Her Majesty.
But using Consent as a stealth veto would be politically problematic. For starters, there is now a convention that the Government always arranges for Consent, even for Private Members’ Bills that they oppose. Furthermore, the Cooper Bill will have an unusual level of support right off the bat since MPs will need to bend the rules if they want to have a chance to debate it. If Ministers try to stop the bill with a procedural technicality, they will be thwarting the clear will of the House.
Craig suggests that this could be less controversial than a true royal veto (i.e., refusing Royal Assent after the bill had passed both Houses of Parliament), but this seems overly optimistic. Withholding the Queen’s Consent would be seen by many, both inside and outside of Parliament, as a dirty trick, and the Queen would be dragged into a vitriolic political controversy. The reality that it was actually a ministerial act would get lost in all the noise (the fact that many media outlets already describe Consent as a ‘secret royal veto’ wouldn’t help, either!).
Interestingly, since the requirement to obtain the Queen’s Consent is a matter of parliamentary practice rather than law, one wonders if Speaker Bercow might be tempted to disregard it and let the Cooper Bill proceed if Consent weren’t forthcoming. If the bill managed to reach the statute book, it couldn’t be invalidated on the grounds that it hadn’t received Consent. However, such a cavalier approach would likely run into difficulties in the Lords since the Lord Speaker can’t wave away procedural obstacles like the Speaker of the Commons can.
The bottom line is that the Government might not like the Cooper Bill, but weaponizing Consent will only make the situation worse.
 See the comments of the then-Leader of the House of Commons quoted in House of Commons Political and Constitutional Reform Committee, The Impact of Queen’s and Prince’s Consent on the Legislative Process (HC 784) (London: The Stationary Office, 2014), para. 25. This has not always been the case, however, and there have been several instances over the years where the Government failed to obtain Consent for Private Members’ Bill that they did not like.
 To formally abolish the practice, MPs would need to present the Queen with an Address asking for permission to dispense with Consent. If it were granted, they could then abolish it by resolution. A similar procedure would be followed in the Lords. See the remarks of the then-Clerk of the House of Commons and the then-Clerk of the Parliaments quoted in Impact of the Queen’s and Prince’s Consent, para. 17.
 See the remarks of Dr. Adam Tucker quoted in Impact of Queen’s and Prince’s Consent, para. 15.