I agree. There does seem to have been a build up of 701s awaiting final acceptance and into service.
There is still a steady stream of 455s departing despite the scrap industry losing capacity (Sims woes).
Which makes me think there must be siding space for more 701s (danger of me being ambitious there !). There certainly will be use for 701s (albeit indirectly via a cascade of 450s and/or 458s)
The number of not in passenger service 701/0s at the London end has been relatively consistent. There's 3 at Farnham, unallocated shuffles make it hard to say which ones are there currently. That leaves 12 between Clapham and Wimbledon broadly similar to before, 4 have joined the in service pool this month roughly offsetting the arrivals.
Some have an operational use e.g. 701028 for PTI testing and there might be others. There's a few on the SWR network since at least this summer without seeing service including 701004, 701015, 701024 and 701054. The next 701s to arrive have a good chance of jumping most of those into service in my opinion.
Three out of four paths were published for a Marchwood to Wimbledon drag for Tuesday this week. Unclear what happened to the Marchwood to Wimbledon schedule to complete the set that didn't appear for whatever reason (light loco Leicester LIP to Eastleigh Yard, Eastleigh Yard to Marchwood and Wimbledon to Leicester LIP were published).
SWR seem to be particularly extreme in this respect.
SWR don't look to be in a position to make changes yet. Introducing additional services requires more crew when there are already plenty of crew availability related cancellations. The current operating model makes time savings on 701s at peak time disappear far more than any ADBO saving. As more 701s get introduced capacity can be increased at peak times across the network at relatively low cost.