Once a claim has been allocated to the small claims track, discontinuance does not automatically entitle the defendant to all of their “pre-discontinuance” costs.
The normal rule in CPR 38.6 is that when a claimant discontinues they must pay the defendant’s costs up to the date of discontinuance. However, CPR 38.6(3) switches that rule off for any case that is proceeding on the small claims track. Once allocated, you are back in the small-claims costs regime, which is CPR 27.14.
That does not mean you can only claim post-discontinuance costs. It means that any costs you claim, whether incurred before or after discontinuance, have to fit within what CPR 27.14 allows.
There are two routes.
First, the “ordinary” small claims costs: fixed issue fee, any hearing fee, and certain limited disbursements such as reasonable travel expenses and witness expenses. Those can include things incurred before discontinuance, but they are a narrow category.
Second, CPR 27.14(2)(g). The court can depart from the no-costs rule and award “such further costs as it may assess on the small claims track” where a party has behaved unreasonably. Under this route you can ask the court to award your reasonable time as a litigant in person at £24 per hour, plus any additional disbursements, to the extent that work was caused by the claimant’s unreasonable behaviour. That can cover work done before discontinuance (for example, dealing with incoherent or non-compliant particulars of claim, having to put them to proof on points they ought never to have pursued, or work forced on you by abusive pre-trial conduct) and work after discontinuance (for example, having to chase them about an N279 signed by someone whose authority they refuse to clarify).
So the short, honest answer is:
You cannot claim your full pre-discontinuance costs “as of right” in the way a fast-track defendant could rely on CPR 38.6. But you can still seek recovery of pre-discontinuance time and expenses if you present them either as ordinary small-claims costs (where they fit that box) or as costs flowing from unreasonable behaviour under CPR 27.14(2)(g). The key is to tie each chunk of time and spend to specific examples of unreasonable conduct and then invite the court, in its discretion, to award those sums.
In this case, a late discontinuance very close to a hearing (or after you have incurred substantial work) can support an application for unreasonable behaviour costs under CPR 27.14(2)(g), especially where, as in this case, the claim was obviously weak or defective from early on (e.g. hopeless PoC, clear PoFA failure, no standing, duplicate claims) and the claimant pressed on, ignored clear rebuttals, then pulled out only at the last minute.